Localized fibrosis of the corpus cavernosum: An example of fibrosis arising from the vascular smooth muscle cells - Report of a case with histogenetic considerations

We report a rare case of a localized fibrosis of the corpus cavernosum (CC) presenting as a nodular mass in the dorsal region of the penis without abn ormal curvature of the organ. Histological and immunohistochemical examinat ion revealed a fibrotic process, involving CC but not tunica albuginea, ari sing from the smooth muscle cells of the vascular channels. Two different m orphological phases were identified in these vascular lesions: proliferativ e and residual phase. The proliferative phase was characterized by hyperpla sia and moderate fibrous thickness of the smooth muscle layer of the vascul ar channels of CC, resulting with the formation of concentric perivascular cuffs and nodules. The residual phase was characterized by a progressive no dular fibrotic transformation with narrowing of the original vascular chann els and replacement of the normal CC structures. The cells of this phase ex hibited an immunophenotype of both fibroblasts (vimentin+; alpha-smooth mus cle actin-) and myofibroblasts (vimentin+; alpha-smooth muscle actin+). The clinicopathological features of the lesion and histogenetic considerations are discussed. Copyright (C) 2000 S. Karger AG. Basel.