AIMS: To document the presence, morphology, immunophenotype and ultrastructure of multinucleated stromal cells within the anal mucosa and to discuss possible pathogenetic mechanisms for this occurrence. METHODS AND RESULTS: Multiple sections of normal anal mucosa from 30 abdominoperineal resection specimens were analysed by light microscopic, electron microscopic and immunohistochemical methods. Multinucleated stromal cells were found in 22 cases (73%). They contained two to five nuclei, arranged in a linear fashion or in a rosette or grape-like pattern. They stained positive for vimentin and negative for actin, desmin and oestrogen/progesterone receptors. Ultrastructural examination confirmed their fibroblastic lineage. Mast cells were frequently observed in the immediate vicinity of mono- and multinucleated cells. CONCLUSIONS: Multinucleated stromal cells are a common occurrence in the normal anal mucosa. They should not be misinterpreted as neoplastic cells. Mast cells may play a role in their morphogenesis.
AIMS: To document the presence, morphology, immunophenotype and ultrastructure of multinucleated stromal cells within the anal mucosa and to discuss possible pathogenetic mechanisms for this occurrence. METHODS AND RESULTS: Multiple sections of normal anal mucosa from 30 abdominoperineal resection specimens were analysed by light microscopic, electron microscopic and immunohistochemical methods. Multinucleated stromal cells were found in 22 cases (73%). They contained two to five nuclei, arranged in a linear fashion or in a rosette or grape-like pattern. They stained positive for vimentin and negative for actin, desmin and oestrogen/progesterone receptors. Ultrastructural examination confirmed their fibroblastic lineage. Mast cells were frequently observed in the immediate vicinity of mono- and multinucleated cells. CONCLUSIONS: Multinucleated stromal cells are a common occurrence in the normal anal mucosa. They should not be misinterpreted as neoplastic cells. Mast cells may play a role in their morphogenesis.