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It can be difficult to differentiate between epithelial and mixed type mesothelioma and metastatic adenocarcinoma. To distinguish between the two, it has recently been suggested that the presence of abluminal microvilli making contact with collagen fibrils through discontinuities in the basal lamina was characteristic of mesothelioma but not of metastatic adenocarcinoma. This study presents three patients out of 39 who had adenocarcinoma metastatic to the pleural and abdominal cavities, in which direct contact was observed between abluminal microvilli and collagen fibrils. All 39 examples of mesothelioma which were also examined demonstrated this feature. This phenomenon should therefore not be used as a discriminator between mesothelioma and metastatic adenocarcinoma. An additional patient with metastatic adenocarcinoma in an axillary lymph node demonstrates that this phenomenon is not limited to the pleural or abdominal cavities.

(1992). Anemone Cell Tumor Revisited. Ultrastructural Pathology: Vol. 16, No. 4, pp. iii-v.

Chordoid tumor--synonymous with chordoid sarcoma, parachordoma, and peripheral chordoma--is a very rare neoplasm with histologic similarity to chordoma that is found outside the axial skeleton. A soft tissue chordoid tumor in the gluteus maximus muscle of a 42-year-old man is presented. This tumor had morphologic features identical to a chordoma: nodular growth with vacuolated cytoplasm and myxomatous stroma by light microscopy, positive immunoreaction for cytokeratin and epithelial membrane antigen by immunohistochemistry, desmosomes, intercellular lumina lined with microvilli, and the presence of basal lamina material by electron microscopy. Two similar cases have been reported in the English literature.

Granular cell tumors (GCTs) were originally characterized ultrastructurally by the presence of many large lysosomes and angulate bodies (ABs). ABs appear to have been forgotten, and the diagnosis of GCT currently depends solely upon the presence of large lysosomes. Most investigators favor a Schwann cell origin for GCT. Recently, reports of granular tumors with large lysosomes but without ABs have suggested other cells of origin. If the ultrastructural criteria for the diagnosis of GCT were maintained as originally described, many of these granular tumors would not qualify as true GCTs. Two granular tumors that were at first considered GCTs are described. Based on the presence of large lysosomes and the presence or absence of ABs, one tumor was considered a true malignant GCT and the other a benign fibroblastic tumor.

A metastatic spindle cell malignant melanoma with positive immunoreactivity for S-100 protein and HMB-45 antigen and the presence of premelanosomes is described in a lymph node of the neck 11 years after removal of a superficial spreading malignant melanoma from the arm. Ultrastructurally, long, slender microvilli created a pattern with great similarity to an anemone cell tumor. A more solid pattern without microvilli was also present. Despite the abundance of microvilli in the anemone part of the tumor, intracytoplasmic lumina were not observed. In addition, crystalline structures within enlarged mitochondria and intracisternal tubules were noted.

A 72-year-old man presented with a 15 × 12 × 5 cm cystic and necrotic tumor involving the superior region of the stomach and the retroperitoneum down to the transverse colon and extending laterally from the left lobe of the liver to the spleen without involving either organ. Light microscopy showed the tumor cells to be arranged in an organoid pattern. Immunocytochemistry showed a strong reaction for desmin and vimentin. Electron microscopy demonstrated features suggestive of an alveolar soft part sarcoma.

Membrane-bound cytoplasmic crystals were found in the intrafusal fibers of a muscle spindle from a patient with neurogenic atrophy. The crystals have a periodicity of 10 nm and an intersecting axis angle of approximately 80 degrees. This makes the crystals similar to those described in alveolar soft part sarcoma (ASPS). Because the crystals in ASPS may not be quite as specific as previously believed, and because similar crystals have been described in various other neoplasms, the present findings should not be taken as evidence for a muscle spindle derivation for ASPS.

The effect of α-difluoromethylornithine (DFMO) treatment on the morphology of African trypanosomes was investigated. For this purpose inbred mice were immunosuppressed and infected with a clone of the protozoan blood parasite Trypanosoma brucei rhodesiense . The mice were then treated with DFMO, an irreversible inhibitor of ornithine decarboxylase, which inhibits polyamine synthesis. DFMO treatment in the absence of host immunity resulted in arrest of cytokinesis of the trypanosomes and many binucleated cells could be seen in blood smears. If mice were infected with a highly virulent trypanosome clone (ETat 1.10), which does not normally transform from long slender (LS) to short stumpy (SS) forms, DFMO treatment caused SS transformation to occur on days 3–4. This morphological SS transformation was substantiated by the presence of diaphorase activity and nuclear and mitochondrial changes. The results suggest a possible involvement of polyamines in the transformation from LS to SS forms.

Cardiac metastasis should be strongly suspected in the cancer patient with sudden onset of unexplained tachycardia, arrhythmia, or congestive heart failure. Conduction defects and low voltage on electrocardiographic examination and an enlarged heart shadow on the chest film are virtually confirmatory. Thirty-eight such patients were treated through anterior and posterior opposing portals and received 2,500-3,500 rads in 3-4 weeks, except for 6 lymphoma and leukemia patients who were controlled with lower doses (1,500-2,000 rads in 11/2-2 weeks). Primary sites and duration of improvement were as follows: breast (11/16 patients): 2-36 months; lung (2/7 patients): 1-9 months; lymphoma and leukemia (6/7 patients): 2-4 months; others (4/8 patients): 1-4 months. Overall, the clinical improvement rate was 60%, with durations of 12 to 36 months.

We report a rare case of malignant oncocytic carci-noid of the pancreas including the diagnostic immu-nocytochemical and electron microscopic findings. In addition the tumor shows some unusual ultra-structural features: lamelliform cristae and cyto-plasmic and nuclear crystalline structures.

Tubular carcinoma of the breast is a recognizable histologic type of invasive mammary carcinoma, characterized by infrequent axillary lymph nodal metastases and an excellent prognosis. Of all carcinomas of the breast diagnosed in 1974 in the Louisville area, 42, or 10.3% were of the tubular variety. This is in contrast to the previously expressed opinion that tubular carcinoma is rare. Three histologic types of tubular carcinoma are described. Strict criteria for diagnosis of the mixed type are recommended.

A renal biopsy of a patient who had systemic lupus erythematosus and proteinuria revealed the presence of both amyloidosis and lupus glomerulonephropathy. The association between secondary amyloidosis and systemic lupus erythematosus has only been reported in four previous cases. The significance of this association is discussed.

Biliary tract obstruction in a 30-year-old man was found to be caused by a malignant melanoma in the common bile duct. Melanin pigment was demonstrated by immunohistochemistry and electron microscopy. Extensive search for a primary malignant melanoma elsewhere was unsuccessful. No pigmented lesions had been removed previously. There were junctional changes in the mucosa of the common bile duct close to the tumor. The malignant melanoma in the common bile duct therefore is considered to be primary. Only one other case of primary malignant melanoma in the common bile duct has been described in the literature, whereas metastases to the major bile ducts in one autopsy study of malignant melanoma in the more common locations were found with a frequency of 6 per cent.

Malignant melanoma originating outside the skin, juxtacutaneous mucous membranes, eyes, and leptomeninges is a very rare neoplasm. Two such primary visceral malignant melanomas from the lung and adrenal are described in detail.

Two cases of infiltrating tubular carcinoma of the breast were studied by electron microscopy. Our findings indicate that these tumors are composed of duct (or ductular) epithelial cells exhibiting varying degrees of differentiation. In the well-differentiated tumor, the cells very closely resembled those of the normal duct with respect to fine structure and polarity. Differences include the more extensive formation of apical and basal cytoplasmic protrusions, and increased numbers of intracellular lumens and tonofilaments. Solid nests of tumor cells were also seen. Myoepithelial or myoepithelial-like cells were rarely observed, and basement membrane investment of the tubules was incomplete or totally lacking. In the less-differentiated tumor, the cells were more pleomorphic and showed loss of polarity, but still formed lumens. The epithelial cells comprising tubular carcinoma were also quite similar in fine structure to the cells found in some reported cases of well-differentiated intraductal and infiltrating duct carcinomas.

This is a report of 35 cases of tubular carcinoma of the breast treated at Memorial Sloan-Kettering Cancer Center from 1938 to 1971. This type of cancer is also known as well-differentiated carcinoma. Ages of patients were 31-75 years with a mean of 50.8 years. In 27 cases the presenting symptom was a mass which had usually been present more than 2 months. In 19 cases the tumor was in the upper outer quadrant of the breast. In 2 cases the cancer was bilateral. Mammograms made for 13 patients were positive in only 6 and questionable in 2 others. In 2 cases small tumors had been incorrectly diagnosed as benign lesions. In 1 fibroadenoma was also present. In 80% of cases other forms of breast carcinoma were also present in the same breast. Of the 35 cases 23(65%) also had foci of intraductal papillary carcinoma. The prognosis is dependent on the associated cancer. In 3 cases (9%) the tubular carcinoma had spread to the axillary nodes. Treatment was by radical mastectomy in 27 instances modified radical in 6 and local excision in 1. Internal mammary resection was done in 1 case. Bilateral radical mastectomy was done in 5. Postoperative radiation was given to 4 patients. Follow-up information of from 1-32 years was available for 23 patients. Local recurrences were found in 2 and 1 there were metastases to the lumbar spine. No deaths were considered due to the tubular cancers. The modified radical mastectomy is considered adequate for most cases.

We have recently had the opportunity to examine two cases, where malignant melanoma was suspected on light microscopy and Fontana-Masson stain was focally and faintly positive. Electron microscopy of four to five different blocks failed, however, to demonstrate the presence of premelanosomes and thereby to confirm the diagnosis of malignant melanoma. The areas in the paraffin blocks that on Fontana-Masson stain had showed a positive reaction were deparaffinized, embedded in plastic, and examined by electron microscopy. Now the characteristic premelanosomes were found and the diagnosis of malignant melanoma was confirmed.

Serial sections from 1 block of either a normal or hyperplastic prostate demonstrated at least 2 foci of perineural invasion in 7 of 8 consecutive autopsies. In addition to the perineural invasion a close relationship was found among nerves, glandular epithelium and vascular structures in all 8 autopsies.Although there are differences between the epithelium in perineural invasion in carcinoma and in normal or hyperplastic prostates perineural invasion can no longer be regarded as unequivocal evidence of malignancy.

The Weibel-Palade body (WPB), a cytoplasmic marker for endothelial cells, was utilized in this ultrastructural study to confirm the light microscopic diagnosis in four different neoplasms of suspected endothelial origin. The WPB was prominent in benign endothelial neoplasms but was less so or absent in the malignant counterpart.

Four cases of small cell carcinoma of the lung were studied ultrastructurally. The tumor cells contained scattered neurosecretory granules. Areas of the tumor that showed the characteristic crush phenomenon were found to be surrounded by myofibroblasts. It is proposed that the crush phenomenon is caused by contraction of the encircling myofibroblasts. The myofibroblasts and collagen may also cause degeneration and necrosis of the tumor cells. Myofibroblasts have not been observed in other histologic types of carcinoma of the lung.

Prominent crystalline inclusions were noted in the glomeruli of a 57-year-old man with a 6-month history of swelling and pain in the hands, slight proteinuria, and elevated serum creatinine and BUN. The crystalline inclusions were most prominent in the visceral epithelium but were also noted in endothelial and mesangial cells, in the parietal epithelium, and in the epithelial cells of the proximal tubules. On electron microscopy the crystalline structures were of various geometric shapes but had no definite substructure. Immunofluorescence was negative. The patient was considered to have a hitherto undescribed metabolic disease. Several months later the patient underwent an operation for carpal tunnel syndrome and amyloid deposits, crystalline inclusions similar to those noted in the kidney were observed in the synovial tissue. Shortly after this the patient was found to have multiple myeloma of IgG, kappa type with Bence Jones proteinuria. Lymphoplasmacytic cells in the bone marrow contained the same crystalline inclusions noted in the kidney and synovium. This case therefore seems to represent a new and very rare form of glomerular involvement in multiple myeloma.

A unique ultrastructural feature in a duodenal carcinoid is described, viz., large juxtanuclear accumulations of microfilaments arranged in whorls. Similar microfilaments are found in the D1 cell of the gastro-entero-pancreatic endocrine system. Apparently identical whorl-like accumulations of filaments have been previously described in bronchial cells of animals treated with nitrosamines and in human giant cell carcinoma of the lung. We suggest that the D1 cell is the cell of origin for the described carcinoid as well as for the above-mentioned tumours of the lung.