Granular cell tumour: malignant or benign?

Granular cell tumours (GrCTs) are uncommon soft tissue tumours that are usually benign (approximately 0.5%-2.0% have been reported as malignant). They are very rarely found at the extremities. Differentiating a malignant GrCT from a benign one is important as the former is aggressive and has a poor prognosis, whereas the latter, after surgical resection, has excellent outcomes. A malignant lesion can be suspected on clinical presentation and confirmed via histopathological examination using the Fanburg-Smith criteria.

This was a retrospective review of all cases of GrCT of the extremities that presented to the Orthopaedic Oncology Unit of University Malaya Medical Centre, Malaysia, from September 2006 to March 2013.

There were a total of five cases, all of which involved female patients aged 13-40 (mean age 24) years. Three cases involved the upper limbs and two involved the lower limbs. Using the Fanburg-Smith criteria, three cases were classified as benign, one as atypical and one as malignant. Wide local excision was performed in all five cases and the outcomes were excellent except for the patient with a malignant tumour. That patient presented with lung metastasis about three months after surgery.

Malignant and benign GrCTs can be differentiated on clinical presentation and by using the Fanburg-Smith criteria. We believe that wide local excision is the best treatment for both benign and malignant tumours. The role of adjuvant chemotherapy and radiotherapy in malignant GrCTs should be studied. All patients with GrCTs should receive follow-up to check for recurrence and metastasis.