RENAUT BODIES - BENIGN DISEASE PROCESS MIMICKING NEUROTROPIC TUMOR INFILTRATION

BACKGROUND. Mohs micrographic surgery maximizes the potential for comp lete tumor removal with normal tissue preservation through the histolo gic examination of all tissue margins. One component of the histologic examination is the evaluation of excised nerves for the presence of t umor infiltration. During such art evaluation, a subperineurial struct ure was noted. OBSERVATION. Further investigation displayed a discrete , loosely textured, cell-sparse, whorled, subperineurial structure tha t invaginated into the peripheral nerve. Inflammation arts absent and the nuclei were monomorphous. These findings are those seen with Renau t bodies. CONCLUSIONS. Renaut bodies are found at sites of nerve compr ession. Mechanical factors are thought to play a major role in pathoge nesis. Cells comprising the Renaut body are fibroblasts of perineurial origin with the extracellular matrix comprised of collagen fibrils, b asal lamina material, and oxytalan filaments Renaut bodies are importa nt insofar as the surgeon must recognize that they are benign. Histolo gic characteristics that differentiate Renaut bodies from malignant ne urotropic infiltration are: (a) a cell-sparse mass, (b) absence of nuc lear atypia, (c) less than expected inflammatory infiltrate, and (d) w ell-defined borders. (C) 1996 by the American Society for Dermatologic Surgery, Inc.