Expanding the clinicopathological spectrum of succinate dehydrogenase-deficient renal cell carcinoma with a focus on variant morphologies: a study of 62 new tumors in 59 patients.

Most succinate dehydrogenase (SDH)-deficient renal cell carcinomas (RCCs) demonstrate stereotypical morphology characterized by bland eosinophilic cells with frequent intracytoplasmic inclusions. However, variant morphologic features have been increasingly recognized. We therefore sought to investigate the incidence and characteristics of SDH-deficient RCC with variant morphologies. We studied a multi-institutional cohort of 62 new SDH-deficient RCCs from 59 patients. The median age at presentation was 39 years (range 19-80), with a slight male predominance (M:F = 1.6:1). A relevant family history was reported in 9 patients (15%). Multifocal or bilateral tumors were identified radiologically in 5 patients (8%). Typical morphology was present at least focally in 59 tumors (95%). Variant morphologies were seen in 13 (21%) and included high-grade nuclear features and various combinations of papillary, solid, and tubular architecture. Necrosis was present in 13 tumors, 7 of which showed variant morphology. All 62 tumors demonstrated loss of SDHB expression by immunohistochemistry. None showed loss of SDHA expression. Germline SDH mutations were reported in all 18 patients for whom the results of testing were known. Among patients for whom follow-up data was available, metastatic disease was reported in 9 cases, 8 of whom had necrosis and/or variant morphology in their primary tumor. Three patients died of disease. In conclusion, variant morphologies and high-grade nuclear features occur in a subset of SDH-deficient RCCs and are associated with more aggressive behavior. We therefore recommend grading all SDH-deficient RCCs and emphasize the need for a low threshold for performing SDHB immunohistochemistry in any difficult to classify renal tumor, particularly if occurring at a younger age.

A histopathological study of melanocytic and pigmented skin lesions in patients with albinism.

BACKGROUND: Oculocutaneous albinism (OCA) is a group of genetic disorders characterized by diminished pigmentation of the skin, hair and eyes. Individuals with OCA are at increased risk to develop sun-induced skin malignancies. The incidence of malignant melanoma in OCA individuals is, however, very low. The aim of this study was to document pigmented and melanocytic skin lesions occurring in patients with OCA. METHODS: A prospective study was performed. Sixteen patients with OCA presenting at the Oncology and Dermatology Departments at Universitas Academic Hospital Annex in Bloemfontein, South Africa, were included. Selected clinically pigmented and/or melanocytic lesions were biopsied and studied by light microscopy. RESULTS: Twenty-four punch biopsies were taken. Ten dendritic freckles and 10 melanocytic nevi were confirmed histologically. The nevi, which occurred in eight patients, were found on sun-protected skin. All the freckles occurred on sun-exposed skin. Twelve patients had current or previous skin malignancies. No melanomas were present in the study population. Other skin lesions ranged from solar keratoses to squamous cell carcinomas. CONCLUSION: The majority of pigmented lesions were dendritic freckles that occurred on sun-exposed skin. None of the patients had a current or previous diagnosis of malignant melanoma.