A suspected malignancy in osteolytic bone tumour of the thumb.

A 75-year-old male patient was referred to our institution owing to a painful and gradually developing lesion of the thumb with suspicious malignancy. The patient was suffering from a swollen, red, tender left thumb for 3 months. An old scar at the finger pulp could be traced from an old minor trauma. The x-ray revealed an osteolytic lesion in the terminal phalanx of the non-dominant hand that raised concerns of malignancy. Additional investigations such as ultrasound, CT-scan and MRI have been performed to get better insight to the lesion. After performing a biopsy, no malignant cells were found. Owing to the local destroying effect of the lesion and the clinical signs of the patient, the lesion was excised in total. The histopathological evaluation confirmed the tumour as a rare intraosseous epidermoid cyst. A bone graft after resection was not needed. The postoperative follow-up of the patient was uneventful.