Immunohistochemical Characterization of Facioscapulohumeral Muscular Dystrophy Muscle Biopsies.

BACKGROUND: Posited pathological mechanisms in Facioscapulohumeral Muscular Dystrophy (FSHD) include activation in somatic tissue of normally silenced genes, increased susceptibility to oxidative stress, and induction of apoptosis. OBJECTIVE: To determine the histopathological changes in FSHD muscle biopsies and compare to possible pathological mechanisms of disease. METHODS: We performed a cross-sectional study on quadriceps muscle biopsies from 32 genetically confirmed FSHD participants, compared to healthy volunteers and myotonic dystrophy type 1 as disease controls. Biopsies were divided into groups to evaluate apoptosis rates, capillary density, myonuclear and satellite cell counts. RESULTS: Apoptosis rates were increased in FSHD (n=10, 0.74%) compared to myotonic dystrophy type 1 (n=10, 0.14%, P=0.003) and healthy volunteers (n=14, 0.13%, P=0.002). Apoptosis was higher in FSHD patients with the smallest residual D4Z4 fragments. Capillary density was decreased in FSHD1 (n=10, 316 capillaries/mm2) compared to healthy volunteers (n=15, 448 capillaries/mm2, P=0.001). No differences were seen in myonuclear or satellite cell counts. CONCLUSIONS: Preliminary evidence for increased apoptosis rates and reduced capillary density may reflect histopathological correlates of disease activity in FSHD. The molecular-pathological correlates to these changes warrants further investigation.

Papillary cystadenoma of the epididymis.

Papillary cystadenoma is a rare benign neoplasm of the epididymis, occurring mainly in young adult males. More than one-third of the cases reported in the literature have occurred in patients with von Hippel-Lindau disease. Conversely, epididymal nodules presumed to be papillary cystadenomas are found in one-third of males with von Hippel-Lindau disease. The association is stronger for bilateral tumors. The pathogenesis involves loss of the von Hippel-Lindau gene resulting in overexpression of the angiogenic protein "hypoxia-inducible factor." Papillary cystadenoma is of mesonephric derivation. It originates in the efferent ductules of the head of the epididymis in the form of tiny precursor lesions. Histologically, papillary cystadenoma is characterized by cystic spaces with intracystic papillary projections lined by clear cells, with a resultant resemblance to renal cell carcinoma. Immunohistochemical markers may facilitate the distinction between the 2 tumors. Treatment consists of surgical excision and the prognosis is excellent.