Primary cutaneous diffuse leiomyosarcoma with desmoplasia


  • Carolyn Choy, FRCPA. Alan Cooper, FACD. Steven Kossard, FACD.

  • Funding for colour figure publication was provided by a grant from the Australasian Dermatopathology Society.

Dr Carolyn Choy, Skin and Cancer Foundation Australia, 277 Bourke Street, Darlinghurst, NSW 2010, Australia. Email:


A 65-year-old man presented with an indurated plaque over his left cheek and left neck. An initial punch biopsy of skin showing increased smooth muscle bundles was consistent with a diagnosis of smooth muscle hamartoma. A second incisional skin biopsy revealed a well-differentiated smooth muscle proliferation invading into the dermis and subcutaneous fat in a diffusely infiltrative pattern and with a desmoplastic component, suggesting a diagnosis of desmoplastic leiomyosarcoma. Resection of the tumour confirmed the presence of a cytologically low grade leiomyosarcoma with an insidious infiltrative growth pattern. This rare pattern of diffuse leiomyosarcoma is important to recognize as the histological features are subtle and may potentially constitute a pitfall in histological diagnosis in a small biopsy specimen. In addition, our case illustrates overlapping morphology between diffuse and desmoplastic types of leiomyosarcoma.