Introduction: Abrikossoff's tumour or granular cell tumour is usually benign involving multiple anatomical sites, most frequently the head, neck and airways. Occasional observations of aggressive malignant tumours have been reported, associated with a poor prognosis.
Case report: We report the case of a mammary Abrikossoff's tumour, initially considered benign and treated solely by local surgery. Seven years later the tumour was responsible for the development of sub-cutaneous and pulmonary metastases. Local surgery was again the only treatment given in the absence of evidence for the effectiveness of alternative treatment with chemotherapy or radiotherapy.
Conclusion: This original observation reports the case of a benign granular cell tumour that underwent malignant transformation after an interval of 7 years as indicated by the clinical progress and the cellular proliferation index Ki-67.