The patient was a 62-year-old man, partially edentulous and not wearing prostheses, smoker since the age of 12 (20 cigarettes a day). He consulted for a painful tumour measuring 5 x 3 cm on the tongue, which had developed over a month, and a weight loss of approximately 6 kg in two months. The tumour was located on the right free edge, extending towards the base of the tongue. There was an ulcer unrelated to chronic dental or prosthetic trauma.

A biopsy of the ulcerated area was taken and histology suggested a differential diagnosis between pseudosarcomatous carcinoma and epithelioid-fusocellular sarcoma.

One month later, pulmonary metastases were seen on chest X-ray, osteolytic images in the dorsal-lumbar spine and two subcutaneous nodules on the dorsum. Biopsy of a dorsal nodule showed the same diagnosis as in the tongue. No treatment was given and the patient was admitted to palliative care and died 6 months later.

Pathological anatomy: tongue biopsy (haematoxylin-eosin): infiltrating and ulcerated epithelioid and fusocellular neoplastic proliferation, with a high mitotic index. Differential diagnosis between pseudosarcomatous carcinoma and epithelioid and spindle cell sarcoma.

Immunohistochemistry: negative pankeratin (AE1-AE3), positive vimentin, negative desmin (positive in non-tumour muscle), negative CD34 and positive actin in spindle cell component (positive intrinsic control in vessels and non-invaded muscle).

Immunohistochemical diagnosis: infiltrating leiomyosarcoma of the tongue.