Cotyledonoid dissecting leiomyoma: case report of a rare subtype

Abstract

Leiomyomas are the most common benign mesenchymal uterine tumour. The vast majority of these have a typical macroscopic and histological appearance. Approximately 10% of leiomyomas are subtyped due to unusual macroscopic or microscopic differences. Cotyledonoid dissecting leiomyomas are considered one of the rarer subtypes of leiomyoma, with distinct macroscopic features that can be worrying for malignancy and require histological correlation for diagnosis. Whilst common leiomyomas will present with a well circumscribed cream cut surface, cotyledonoid dissecting leiomyomas often present as a large fungating mass with a red to brown nodular appearance. Despite the macroscopic differences, histologically, these nodules show the typical benign spindled smooth muscle cells that are found in the classic type. This report presents a case of cotyledonoid dissecting leiomyoma where both clinical and radiological review were unable to ascertain the nature of the lesion, given the unusual macroscopic appearance, and a definitive histological diagnosis was required.