Chordomas of the mediastinum: clinicopathologic, immunohistochemical, and ultrastructural study of six cases presenting as posterior mediastinal masses

Six cases of chordomas presenting as primary posterior mediastinal tumors are described. Three patients were female, and three were male between the ages of 8 and 65 years (mean, 40.6 years). In all cases, the tumors presented radiographically as relatively well-circumscribed, encapsulated soft tissue masses that did not seem to be related to the thoracic or dorsal spine. Only in one case, focal infiltration of bone at the level of T6-T7 was observed at the time of surgery. Histologically, the lesions showed a spectrum of features that ranged from sheets and cords of large cells with abundant vacuolated cytoplasm to small, stellate cells embedded within an abundant mucoid matrix. In one case, the cell population showed more pronounced nuclear atypia with loss of cytoplasmic vacuolization, frequent mitotic figures, necrosis, and solid areas characterized by a perivascular distribution of atypical spindle cells set against a myxoid stroma. Another case showed features of chondroid chordoma, with an immature chondroid-appearing matrix surrounding the atypical tumor cells. Immunohistochemical studies in all cases showed positive staining of the tumor cells with CAM 5.2 and broad-spectrum keratin, epithelial membrane antigen (EMA) and vimentin, and, to a lesser extent, with S-100 protein. Stains for muscle actin, carcinoembryonic antigen (CEA), and desmin were negative. Ultrastructural examination in two cases showed a spectrum of features that varied from large cells with abundant cytoplasm containing scattered ribosomes, glycogen granules, Golgi apparatti, abundant intermediate filaments, and small lumen formation with immature microvilli to smaller cells with elongated cytoplasmic processes, fewer intermediate filaments, rare desmosome type intercellular junctions, and complexes of mitochondria/rough endoplasmic reticulum. On clinical follow-up, two patients died with metastases to the lungs, chest wall, and liver from 1 to 3 years after diagnosis, and two patients are alive and well without evidence of disease after 3 and 16 years. Chordoma should be entertained in the differential diagnosis of posterior mediastinal tumors. Application of immunohistochemical stains or electron microscopy will be of aid in separating them from other conditions that may histologically closely resemble these lesions.     

Donor leukocyte transfusion as treatment for relapsed chronic myelogenous leukemia after allogeneic bone marrow transplantation

We reviewed 4 cases of high-grade transitional-cell carcinoma (TCC) of the urinary tract with solitary pulmonary metastases that were studied by transthoracic needle aspiration biopsy cytology. There were two grade II and two grade III TCCs. The two grade II tumors yielded, in needle aspirates, syncytial tumor-cell clusters showing ill-defined, granular cytoplasm and slightly pleomorphic nuclei with inconspicuous nucleoli. In one case the tumor-cell cluster showed a focal acinar arrangement, mimicking cells of an adenocarcinoma. In both cases the electron microscopy (EM) study of aspirated tumor cells revealed epithelial cells with well-formed cell junctions, intracytoplasmic vesicles, apical short microvilli, and focal interdigitation of lateral cell membranes, suggesting a urothelial neoplasm. The two grade III TCCs yielded, in needle aspirates, pleomorphic malignant cells singly and in small clusters, showing well-defined, granular cytoplasm and pleomorphic nuclei containing prominent nucleoli, suggesting a poorly differentiated adenocarcinoma or an anaplastic large-cell carcinoma. By EM examination the aspirated tumor cells from one case revealed well-formed cell junctions, intracytoplasmic vesicles, poorly formed microvilli, and focal interdigitation of lateral cell membranes, suggesting a urothelial differentiation. In the other case the tumor cells were pleomorphic cells with occasional cell junctions and no ultrastructural features as seen in the other 3 cases of TCC. The tumor cells from the two grade II TCCs showed strong immunopositive reaction with keratin 7 antibody and weakly positive reaction with carcinoembryonic antigen antibody (CEAA), while those of the two grade III TCCs displayed only a weak and focal immunopositive staining with keratin 7 antibody and strong reaction with CEAA.     

Neuroendocrine differentiation in 32 cases of so-called sclerosing hemangioma of the lung: identified by immunohistochemical and ultrastructural study

Thirty-two cases of so-called sclerosing hemangioma of the lung observed by light microscopy were further studied by electron microscopy and/or immunohistochemistry. Three histologic patterns were seen: hemangioma-like, papillary, and solid. The only significant component representing the nature of the lesion is characteristic round cells within the stroma in all these patterns, whereas the surface cells lining the papillary projections or cystic spaces are normal or are hyperplastic bronchioloalveolar cells with a few neuroendocrine cells. Immunohistochemical findings showed that the "stromal cells" (tumor cells) were positive for neuroendocrine markers, namely, chromogranin A (19 of 22 cases), neuron-specific enolase (24 of 24), synaptophysin (six of 10), adrenocorticotropic hormone (14 of 15), growth hormone (14 of 15), calcitonin (11 of 15), and gastrin (11 of 14). Besides, some tumor cells were positive for epithelial membrane antigen (four of four), carcinoembryonic antigen (one of four), and vimentin (one of one). All tumor cells were negative for polyclonal antikeratin antibody (25 cases), AE1 (one case), and AE3 (one case). However, in contrast to the "stromal cells," the surface cells of the cystic spaces stained positively for keratin (25 of 25 cases), AE1 (one of one), AE3 (one of one), epithelial membrance antigen (four of four), and carcinoembryonic antigen (four of four); only a few of them expressed neruoendocrine markers. Both surface and tumor cells were negative for factor VIII-related antigen (25 cases), CD31 (one case), and alpha1-antitrypsin (25 cases). Ten cases further studied by electron microscopy and six examined by ultrastructural morphometry showed that the surface cells were mainly type 2 pneumocytes containing many lamellar bodies in the cytoplasm. Lying among them, neuroendocrine cells were occasionally seen. The stromal tumor cells had no lamellar body, but dense core granules (neurosecretory granules) and microtubules. In six cases, 92.3% (345 of 374) of tumor cells contained neurosecretory granules, which were pleomorphic and 73 to 1056 nm in diameter (mean, 302 nm). Two to 193 (mean, 12) neurosecretory granules were found in each tumor cell. Both immunohistochemical findings and ultrastructural evidence indicate that so-called sclerosing hemangioma of the lung is a benign lesion composed of neoplastic neuroendocrine cells with areas of sclerosis. A suggested name for this tumor is benign neuroendocrine tumor of the lung. The differentiation between this tumor and papillary adenoma, bronchioloalveolar carcinoma, or carcinoid tumor of the lung is discussed.     

Palpebral amelanotic melanomas in F344 rats

Spontaneous amelanotic melanomas in the eyelids of F344 rats were found in one of 1/926 (0.11%) male and 5/925 (0.54%) female F344 rats that were used as control and treated animals in five different carcinogenicity studies conducted by the National Toxicology Program (Research Triangle Park, NC). These melanomas were grossly recognized as single, tan or white, well-circumscribed masses of the right or left eyelid. These melanomas primarily occurred in the dermis of the skin of the eyelids and consisted of poorly differentiated spindle cells characteristically arranged in interlacing fascicles. Rarely, epithelioid tumor cells were also observed, and these tumor cells showed a negative histochemical reaction for melanin. The epidermis and dermal-epidermal junction were usually uninvolved. The diagnosis of amelanotic melanoma could only be established by electron microscopic examination. The most striking ultrastructural feature of the tumor cells was a large number of intracytoplasmic premelanosomes (stage II melanosomes without melanin), which nearly filled the cytoplasm of most tumor cells. Giant premelanosomes and melanophagosomes were also seen. The tumor cells did not possess the ultrastructural features characteristics of Schwann cells (thin, long cell processes and pericytoplasmic basal laminae). The histologic and ultrastructural features of these palpebral tumors were similar to those of cutaneous amelanotic melanomas of the pinna in F344 rats.     

An autopsy case of extraskeletal Ewing's sarcoma followed up for 24 years

A long-term (24 years) follow-up case of extraskeletal Ewing's sarcoma is reported. The light microscopic examination showed features hardly indistinguishable from Ewing's sarcoma of the bone, that is, the tumor cells were diffusely arranged and uniform in size and shape, and possessed glycogen in the cytoplasm. Homer-Wright rosettes were found only in the autopsy material. An immunohistochemical study using a neural marker (neuron-specific enolase) demonstrated positive staining in most tumor cells. An ultrastructural study revealed intracytoplasmic glycogen particles and incomplete neural characters as follows: the cytoplasmic processes resembled neural processes without neurosecretory granules, microtubules or neurofilaments. These findings suggest that this case finally acquired an incomplete neural character with repeated recurrence. This tumor was diagnosed extraskeletal Ewing's sarcoma, but in future it may be categorized as primitive neuroectodermal tumor (PNET).     

Permethrin-treated bed nets do not have a ''mass-killing effect'' on village populations of Anopheles gambiae s.l. in The Gambia

Juvenile hyaline fibromatosis is a multisystemic disorder characterized by a triad of cephalic fibrous outgrowths, gingival hyperplasia, and flexion contractures. The aim of this study was to find new ultrastructural features that could be useful for differentiating this entity from other types of fibromatosis. Mucosal lesions processed for light and electron microscopy by routine techniques showed hyperactive-appearing spindle-shaped fibroblasts and dysplastic mesenchymal cells. Dilated rough endoplasmic reticulum, prominent Golgi complexes, and multivesicular bodies as well as single membrane vesicles filled with fibrillogranular material were seen within the cytoplasm of dysplastic mesenchymal cells. Many fibrillogranular vesicles contained smaller vesicles. There were also invaginations of the cell membrane that contained fibrillogranular material similar to that seen in the single membrane vesicles, suggesting engulfment of an extracellular substance. The stroma contained both normal and serrated collagen fibrils, microfibrils, and two types of fibrillogranular material, one of them with a characteristic banding pattern. Our clinical and histopathologic findings resemble those previously described in cases of infantile systemic hyalinosis and juvenile hyaline fibromatosis. So many features of these two conditions overlap that it is difficult not to consider them as parts of a spectrum of the same disorder.     

Clear cell "sugar" tumor of the lung: association with lymphangioleiomyomatosis and multifocal micronodular pneumocyte hyperplasia in a patient with tuberous sclerosis

We report the unique association of a clear cell "sugar" tumor of the lung (CCTL) in a 32-year-old woman with tuberous sclerosis (TSC), lymphangioleiomyomatosis (LAM), and multifocal micronodular pneumocyte hyperplasia (MMPH). Chest radiographs demonstrated a peripheral solitary 1.0-cm lingular nodule, diffuse emphysematous changes, and bilateral pneumothorax. Microscopic examination of the coin lesion showed an unencapsulated tumor composed of round to oval to focally spindled cells with distinct cellular borders, abundant clear to eosinophilic granular cytoplasm, prominent thin-walled blood channels, and focal hyaline stroma. Rare multinucleated cells were identified, and neither necrosis nor mitotic figures were seen. Tumor cells contained abundant diastase-sensitive intracytoplasmic glycogen, as demonstrated with periodic acid-Schiff stains. Tumor cell immunoreactivity for HMB-45 and nonreactivity for cytokeratin supported the diagnosis. The lung tissue also contained MMPH and smooth muscle proliferations diagnostic of LAM. The histogenesis of CCTL remains controversial, and similarities between this lesion and both LAM and angiomyolipoma (AML) raise the possibility that these lesions are related not only to each other, but that CCTL should be added to the spectrum of pulmonary manifestations of TSC.     

Clear cell differentiation in choroidal melanoma. COMS report no. 8. Collaborative Ocular Melanoma Study Group

OBJECTIVE: To describe 2 enucleated eyes of patients enrolled in the Collaborative Ocular Melanoma Study that contained primary choroidal melanoma with clear cell features. METHODS: During a 9-year period, 1493 eyes enucleated as part of the Collaborative Ocular Melanoma Study routinely processed for histologic examination were evaluated by the pathology review committee (H.E.G, D.M.A, and W.R.G). Two eyes with unusual variants of choroidal melanoma were identified and immunostained for S100 protein and HMB 45. Portions of the tumors were processed for electron microscopic examination. RESULTS: Results of electron microscopic examination of both tumors displayed malignant melanoma (mixed cell type with many malignant cells with clear cytoplasm). The cytoplasm of the clear cells stained with periodic acid-Schiff and failed to stain when pretreated with diastase. Results of immunohistochemical stains in both tumors were positive for S100 protein and HMB 45 in the tumor cells. Results of electron microscopic examination showed that the cytoplasm of the clear cells contained scattered glycogen granules, premelanosomes, and melanosomes. CONCLUSION: These cases represent a clear cell variant of malignant melanoma of the choroid. This tumor should not be confused with metastatic clear cell carcinoma to the choroid.     

Renal myxoma. A report of two cases and review of the literature

Renal myxomas are rare neoplasms. Seven cases have been reported, of which only two are convincingly diagnosed as myxoma; the remaining cases exhibit features of sarcoma, fibroepithelial polyp, or myxolipoma. We report two additional cases; one in a 52-year-old man and another in a 68-year-old woman. They were discovered incidentally by radiological examination. The resected kidney in both patients contained a well-demarcated gelatinous intraparenchymal tumor, which consisted of occasional slender spindle cells scattered in an abundant myxoid stroma, closely resembling myxomas of other sites. The tumor cells showed immunoreactivity for vimentin but not for S-100 protein, epithelial membrane antigen (EMA), CAM 5.2, HHF-35, or smooth muscle actin. Ultrastructural features were of fibroblast-like cells with an elaborate network of cytoplasmic processes. The differential diagnosis of myxoid tumors of the kidney includes myxoid variants of renal sarcomas and carcinomas, renomedullary interstitial cell tumors, and fibroepithelial polyps. It is important to recognize the existence of a renal myxoma, to avoid confusing this benign tumor with the malignant neoplasms with secondary myxoid features that may involve the kidney.     

Immortalized mouse brain endothelial cells are ultrastructurally similar to endothelial cells and respond to astrocyte-conditioned medium

Studies of brain microvessel endothelial cell physiology and blood-brain barrier properties are often hampered by the requirement of repeatedly producing and characterizing primary endothelial cell cultures. The use of viral oncogenes to produce several immortalized brain microvessel cell lines has been reported. The resulting cell lines express many properties of the blood-brain barrier phenotype but do not completely mimic primary endothelial cells in culture. As immortalized brain microvessel endothelial cell lines have not yet been produced from mice, we transformed mouse brain endothelial cells with the adenovirus E1A gene using a retroviral vector (DOL). Eight of 11 clones produced exhibited an endothelial-like cobblestone morphology and were characterized as endothelial with a panel of antibodies, lectins, and ultrastructural criteria. These cells are endothelial in origin and share ultrastructural features with primary cultures of endothelial cells. Examination of freeze fracture and transmission electron micrographs show adherens junctions exist between the transformed cells, and culture in astrocyte-conditioned medium induces the formation of gap junctions. This is one indication that responses to astrocyte-derived factors are retained by the transformed cell lines.     

Pigmented squamous cell carcinoma of the skin: report of two cases and review of the literature

Melanoma is the most common malignant tumor in which melanin synthesis occurs, although other nonmelanocytic tumors synthesize melanin or contain nonneoplastic melanocytes. We present two cases of infiltrating pigmented squamous cell carcinoma of the skin and review the clinical, morphologic, and ultrastructural features. Melanin was found in epithelial tumor cells as well as in macrophages and dendritic melanocytes. Interestingly, one of the neoplasms was associated with an adjacent melanocytic nevus and pigmented solar keratosis. Immunohistochemical analysis showed that neoplastic cells stained for keratin and melanin-filled dendritic cells were found to be S-100 protein and HMB45 positive. A careless examination of the immunohistochemical stains for S-100 protein and HMB45 could cause the misdiagnosis of melanoma, a neoplasm that has a more ominous outlook.     

Granular cell tumor of the duodenum: a case report

Granular cell tumor (GCT) in the duodenum is an extremely rare disease: only one case has been listed in a review, to date. We reported a 47-yr-old Japanese male case with GCT of the duodenum. Clinically, melena caused by bleeding from the tumor was the only symptom. The tumor cells showed abundant, granular eosinophilic cytoplasm. Although this tumor was clinically and histologically benign, highly developed tumor microvessels were demonstrated both angiographically and histologically, suggesting malignant potential of the tumor.     

Atypical angiomyolipoma of the kidney: a distinct morphologic variant that is easily confused with a variety of malignant neoplasms

BACKGROUND: The purpose of this study was to fully characterize and emphasize the salient features of an unusual variant of angiomyolipoma that the authors believe has been underrecognized. METHODS: Five cases of atypical angiomyolipoma (AAML) of the kidney, two of which were reported previously, were retrieved from the consultation files of one of the authors. In one patient a small extrarenal tumor was examined in addition to the primary renal tumor. The histopathologic features of all six tumors, the immunohistochemical findings of five tumors (including the extrarenal tumor), and the ultrastructure of three tumors were analyzed. Clinical follow-up was obtained for all patients. RESULTS: Two tumors occurred in children and presented as large masses (> or = 15 cm), and 2 tumors were small (< 5 cm) and affected middle-aged adults; the remaining tumor, of intermediate size (6 cm), occurred in an adolescent. One child with tuberous sclerosis also had a small (2 cm) extrarenal lesion. All tumors were circumscribed and had a red-brown cut surface. The largest tumors showed areas of hemorrhage and necrosis. The tumors were highly cellular and composed of various types of multinucleated and mononuclear cells. The most distinguishing of these, and virtually pathognomonic of this entity, were huge cells with abnormal strap-like and ameboid configurations having copious eosinophilic hyaline cytoplasm and myriad nuclei disposed peripherally in a ring-like fashion. Ganglion-like cells, polygonal cells, and spindle cells also were observed. For the most part, all cell types shared the same nuclear features, and except for one tumor, mitoses were negligible. The cells displayed a perivascular arrangement, and grew as loosely organized sheets oriented around abnormally dilated vascular channels or in a hemangiopericytic pattern; glomeruloid vessels were variably present. Notably, adipose tissue was inconspicuous. The tumors stained positive for HMB-45 protein, smooth muscle specific actin, and muscle specific actin antibodies, with a tendency for immunoreactivity to segregate along with individual cell phenotypes. Immunoperoxidase stains also disclosed a prominent and consistent intratumoral histiocytic component and a T-cell lymphoid infiltrate. Ultrastructurally, the tumor cells were replete with organelles showing highly electron-dense granules. All patients underwent radical nephrectomy; three patients with significant follow-up remain free of disease. CONCLUSIONS: AAML exhibits unusual but distinctive "pseudomalignant" histomorphologic features that facilitate its recognition, and a singular immunohistochemical profile that allows diagnostic confirmation. It occurs both sporadically and in association with tuberous sclerosis, affects both the adult and pediatric populations, and has shown an indolent behavior. AAML attests to the biologic and morphologic diversity that characterizes tuberous sclerosis hamartomata in general, and to the plasticity of the yet unclarified precursor of angiomyolipoma in particular.     

Pediatric malignant glioma with tubuloreticular inclusions and MYCN amplification. Report of a case with immunohistochemical, ultrastructural, flow cytometric, karyotypic, and Southern blot analysis

BACKGROUND: The authors described unusual pathologic features in a left frontal lobe malignant glioma in a 31/2-year-old boy. The pathology was similar in the initial excision and two subsequent recurrences at 9 and 11 months and at autopsy, when extensive subarachnoid spread was noted. METHODS: The tumor was studied by conventional histology, immunohistochemistry, flow cytometry, transmission electron microscopy (TEM), immune electron microscopy (IEM), and cytogenetic and Southern blot analysis. RESULTS: The tumor revealed two different histologic patterns. One component showed large cells with eosinophilic cytoplasm, vesicular nuclei with prominent nucleoli, eosinophilic perinuclear inclusions, and immunoreactivity for glial fibrillary acidic protein (GFAP) and vimentin. The other component consisted of undifferentiated cells with hyperchromatic nuclei and scanty cytoplasm. By TEM, the perinuclear aggregates were composed of tubuloreticular inclusions, which were also observed in endothelial cells within the tumor vasculature. By IEM, the intermediate filaments in the tumor cell cytoplasm were decorated with GFAP. Flow cytometric results revealed a marked increase in the S-phase (48%), whereas cytogenetic analysis of short-term cultures showed an abnormal karyotype containing marker chromosomes and double minutes. In the second resection, additional karyotypic abnormalities were noted, including 1p- and several additional markers. The first and second resections showed MYCN amplification by Southern Blot analysis in the 60- to 80-fold range. CONCLUSIONS: This tumor presents unique histologic, ultrastructural, and cytogenetic findings as well as MYCN amplification that is notable for a pediatric malignant glioma. Tubuloreticular inclusions were a prominent feature in this tumor, which again is unique for a glioma.     

Prospective, randomized, double-blind study of high-dose aprotinin in pediatric cardiac operations

OBJECTIVE: To describe the characteristic cytologic features of fine needle aspirates (FNAs) of primary extragonadal germ cell tumors (PEGCTs). STUDY DESIGN: Thirteen patients with PEGCTs, including 2 seminomas, 2 mixed germ cell tumors, 3 immature teratomas, 1 choriocarcinoma and 5 yolk sac tumors (YSTs) were studied. The final diagnosis of PEGCT in all cases was established by histologic examination of the tumor tissues. Fine needle aspiration was done on either the primary tumor or metastatic foci. The aspirates were stained with one of the Romanovsky stains and Papanicolaou stain. RESULTS: Each type of PEGCT has its own morphologic characteristics. In seminoma, the tumor cells are large and noncohesive, with one to several distinct nucleoli; some lymphocytes are also present. YSTs show many pleomorphic cells with vacuoles in the cytoplasm and nuclei; tumor cells frequently aggregate in a microglandular or papillary pattern. Choriocarcinoma consists of syncytiotrophoblasts and cytotrophoblasts. The former are very large cells with eosinophilic cytoplasm, one to several nuclei and distinct nucleoli; the latter are medium-sized cells with vacuolated, basophilic cytoplasm and eccentric nuclei. Immature teratomas are composed of a mixture of cell types, including elongated epithelioid cells, mesenchymal cells and many large, naked, amorphous nuclei with a homogeneous chromatin pattern. Diagnosis of mixed germ cell tumor is difficult but can be made if two or more subtypes of tumor cells are observed in the FNA. CONCLUSION: Cytologic examination of FNAs of primary or metastatic lesions of PEGCTs, stained either with Romanovsky or Papanicolaou stain, is of diagnostic value for such diseases. The use of immunochemistry can help to confirm the cytologic impression.     

Sertoli cell tumors of the testis, not otherwise specified: a clinicopathologic analysis of 60 cases

Sixty Sertoli cell tumors of the testis, excluding large cell calcifying and sclerosing subtypes, are described. Patient age ranged from 15 to 80 years (mean, 45 years). The initial manifestation was usually a testicular mass; in 14 cases it had been enlarging slowly for a period of up to 14 years (mean 3.7 years). Only five patients had testicular pain. Four patients had metastatic disease at the time of presentation. All the tumors were unilateral and ranged from 0.3 cm to 15 cm (mean 3.6 cm). They were typically well circumscribed. Sectioning usually disclosed firm, tan-gray, white, or yellow tissue with areas of hemorrhage and a minor cystic component in approximately one third. Microscopic evaluation usually revealed diffuse sheets or large, nodular aggregates of tumor cells, within which solid or hollow, sometimes dilated, tubules and, less often, cords were usually at least focally identifiable. A relatively acellular, often vascular, fibrous to hyalinized stroma was frequently conspicuous. The tumor cells typically had moderate amounts of pale to lightly eosinophilic cytoplasm, but 10 tumors had cells with abundant eosinophilic cytoplasm. Large cytoplasmic vacuoles were prominent in 26 tumors. Nuclear atypicality was absent or mild in 54 cases, moderate in 4 cases, and marked in 2 cases. Mitotic rate ranged from less than 1 to 21 per 10 high power fields, with 50 tumors having no or only rare mitoses. Vascular space invasion was present in 11 cases and was prominent in 8. Follow-up of more than five years (average 8.4 years), or until evidence of metastasis was seen, was available for 16 patients. Nine were alive and well with no evidence of disease. Four were alive with disease and three died of disease. The pathologic features that best correlated with a clinically malignant course were as follows: a tumor diameter of 5.0 cm or greater, necrosis, moderate to severe nuclear atypia, vascular invasion and a mitotic rate of more than 5 mitoses per 10 high power fields. Only one of nine benign tumors for which follow-up data of 5 years or more were available had more than one of these features, whereas five of seven malignant tumors had at least three.     

Fine needle aspiration cytology of acinar cell carcinoma of the pancreas: a report of two cases

BACKGROUND: Fine needle aspiration in lieu of needle biopsy is widely used for the diagnosis of pancreatic neoplasms. The cytologic features of ductal carcinomas are well characterized, but the appearances of less common pancreatic neoplasms, such as acinar cell carcinoma (ACC), are not well described. CASES: We present the cytologic, histologic, immunocytochemical and ultrastructural features of two cases of ACC. The tumors occurred in a 36-year-old woman and 43-year-old man. The aspirate from one case contained neoplastic cells with smooth-contoured nuclei containing one or two prominent nucleoli. The aspirated material from the second case was necrotic, with numerous neutrophils and scattered nests of tumor cells similar to those present in the first case. Histologically, both tumors manifested solid and acinar patterns, and each contained some cells with periodic acid-Schiff-positive granules that were resistant to diastase. The neoplasms were immunochemically positive for trypsin and negative for neuroendocrine markers. Ultrastructurally, the aspirate from one case demonstrated apical microvilli, zymogenlike granules and abundant rough endoplasmic reticulum. CONCLUSION: Uncommon pancreatic neoplasms may be difficult to diagnose due to their cytologic and histologic subtleties. Supplemental studies including immunocytochemistry, cytochemistry and electron microscopy are important in facilitating their identification.     

The fine structure of Walker 256 carcinoma cells

Several ultrastructural features of Walker 256 rat tumor cells which have not been observed before are revealed. Nuclear bodies either singlely or in pairs were found in some cells. Cytofilaments were observed in the cytoplasm and cytoplasmic projections in a few cells. Desmosomes which are usually regarded as a feature of differentiated cells were also observed.     

Use of post-column fluorescence derivatization to develop a liquid chromatographic assay for ranitidine and its metabolites in biological fluids

OBJECTIVE: To describe the cytologic features of solid and cystic tumor of the pancreas. STUDY DESIGN: Cytologic features of four cases of solid and cystic tumor of the pancreas (SCT) were reported and compared with those of three cases of islet cell tumor of the pancreas. RESULTS: Aspiration and imprint cytology of the tumor cells obtained from three cases of SCT showed papillary structures or rosette formations in part and demonstrated uniformly round to oval nuclei that contained finely granular chromatin, a fairly distinct nucleolus and a scant to moderate amount of granular or vesicular cytoplasm. Another case of SCT consisted of multinucleated giant cells with coherent chromatin as well as mononuclear cells with nuclear grooves. Islet cell tumor consisted mainly of clustered or isolated uniform mononuclear cells with rosette formations but without a papillary structure and occasional multinucleated giant cells in all cases. The nuclei of islet cell tumors had peculiar, fine chromatin aggregates with a "salt-and-pepper" appearance and slightly enlarged nucleoli. CONCLUSION: SCT is cytologically distinguishable from islet cell tumor in spite of having many cytologic features in common with it.