Malignant fibrous histiocytoma of the conjunctiva.

We report the clinical and pathological findings in a case of malignant fibrous histiocytoma in the conjunctiva of a 60-year-old man. The patient initially had an atypical limbal lesion, resembling a pterygium, which was excised. Two local recurrences, noted during the following year, were treated by surgical excision followed by cryotherapy. Histopathologic examination of the conjunctival lesions showed a stromal neoplastic infiltrate composed of atypical spindle cells and histiocytelike cells. The immunohistochemical and ultrastructural studies suggested that the tumor was composed of various cellular elements: fibroblasts, myofibroblasts, and histiocytes.

Insular (poorly differentiated) carcinoma of the thyroid: an ultrastructural and immunocytochemical study of two cases.

Two cases of pure insular (poorly differentiated) carcinoma of the thyroid are reported, with emphasis on their ultrastructure. Notwithstanding their solid/primitive histologic character, a high degree of structural organization and differentiation was present at the submicroscopic level, namely a highly developed cytosecretory apparatus and numerous abortive/rudimentary follicles. A prominent inclusion/dot-like pattern (often paranuclear) of thyroglobulin immunoreactivity was observed, ultrastructurally corresponding to the following features: a) abortive/rudimentary follicular lumina with abundant periluminal dense bodies, and with varying amounts of colloid and microvilli, both at the intercellular and intracellular level; b) large inclusions of fibrillar/lamellar or finely granular material within dilated cisternae of endoplasmic reticulum and possibly of lysosomal nature as well, likely reflecting altered production and/or storage of thyroglobulin substrate. One tumor had many cytophenotypical attributes ascribed to differentiated papillary carcinoma (PC), whereas the other tumor was more analogous to differentiated follicular carcinoma (FC). The present study supports the concept that the insular pattern is a common pathway of dedifferentiation for follicular cell neoplasia of both PC and FC types, yet with maintenance of most of their respective cytophenotypical features, and with evidence of a high level of differentiation/maturation at the submicroscopic level.

Metastasis to the optic nerve: clinicopathological correlations.

OBJECTIVE: To describe the clinical, radiologic and histopathological features of two cases of carcinoma metastatic to the optic nerve with different pathways of spread. DESIGN: Chart review. SETTING: Oncology clinic in Montreal. PATIENTS: One patient previously treated for breast carcinoma and one patient previously treated for small-cell carcinoma of the lung. RESULTS: The patient with breast carcinoma was found to have an elevated mass involving her right optic nerve head. This finding was confirmed by B-scan ultrasonography. The other patient initially presented with left retinal metastasis and subsequently manifested massive secondary involvement of the ipsilateral optic nerve, documented by computed tomography. Both patients were initially treated with radiotherapy to the eye and orbit, but postmortem histopathological study showed that this treatment had little effect on the tumour. CONCLUSIONS: The histopathological observations suggest that if radiotherapy is to be used in the treatment of metastasis to the optic nerve, the dosage of radiation should be higher than that recommended for the treatment of choroidal metastasis.

Reticulohistiocytoma of the limbus and cornea. A clinicopathologic study of two cases.

Reticulohistiocytoma is a rare, benign histiocytic lesion usually occurring as an isolated skin nodule or as part of a systemic disorder known as "multicentric reticulohistiocytosis." The clinical and histopathologic findings of two women who presented with a single, painless mass localized to the cornea and limbus without skin lesions or systemic disease are reported. Histopathologically, the lesions were composed predominantly of large mononuclear and a few multinucleated cells with finely granular, "ground-glass" cytoplasm and large nuclei with prominent nucleoli. Immunohistochemical and electron microscopic studies conformed the histiocytic nature of these cells. Reticulohistiocytoma should be included in the differential diagnosis of epibulbar benign histiocytic lesions.

Talc in liver tissue of intravenous drug abusers with chronic hepatitis. A comparative study.

To determine the frequency of talc microcrystals in liver tissue of intravenous (IV) drug abusers and the significance of this finding, the authors reviewed, with light and polarizing microscopy, sections of liver tissue from 70 patients with chronic hepatitis and a history of active (45) or past (25) IV drug abuse. Birefringent crystalline particles consistent with talc were found in 44 cases (63%), 31 associated with active and 13 with past drug abuse. The microcrystals were situated predominantly in hypertrophied portal macrophages; there were no well-formed granulomas. Scanning electron microscopic and energy-dispersive spectrophotometry performed on eight of the positive cases showed the characteristic "flake-pastry" appearance and chemical composition (silicon and magnesium) of talc. For comparison, the authors similarly examined 70 cases of posttransfusion chronic hepatitis, all of which had negative findings for talc, and 70 cases of chronic hepatitis with no documented risk factors for viral hepatitis, of which two had positive findings for talc, even though IV drug abuse was denied by the two patients. The authors conclude that talc is frequently present in the liver of IV drug abusers and whenever encountered it strongly suggests IV drug abuse. Only two patients (1.4%) with a negative history also had talc.

Bile duct adenoma. A study of 152 cases.

In order to determine the morphologic spectrum of bile duct adenoma (BDA), we reviewed the clinical, gross, and histopathological features of 152 cases. All BDA were asymptomatic nodules discovered incidentally during intra-abdominal surgery (103 cases) or at autopsy (49 cases). They were usually subcapsular, ranged in size from 1 to 20 mm (mean, 5.8 mm), and were well circumscribed but nonencapsulated. Histologically, BDA was composed of benign, noncystic ductules and variable degrees of inflammation and fibrosis. The immunophenotype of these ductules was similar to that of interlobular bile ducts. Follow-up of 38 of the surgically treated patients confirmed the benign behavior of this lesion. BDA should be distinguished from an adenocarcinoma by the absence, in the former, of nuclear hyperchromasia, mitotic activity, and vascular invasion. The absence of bile and cystic changes and lack of association with polycystic disease of the liver and kidneys are the main features distinguishing BDA from von Meyenburg complex. We believe that BDA is a reactive process to a focal injury rather than a true neoplasm or a developmental anomaly.