Giant trichoblastoma of the scalp

Trichoblastoma is a rare and benign adnexial tumor with characteristic histological features. It occurs on any hair folliclebearing location, and usually presents as a solitary lesion most often less than 2 cm in size. Giant trichoblastoma has been rarely reported in the literature.

To report a new case of giant trichoblastoma, misleading for malignancy.

A 57-year-old woman presented with a 5 cm-solitary asymptomatic nodular lesion of the scalp, of 28 years. It had been previously excised with recurrence and progressive regrowth. On examination, it was a dome-shaped, erythematous, firm, papillomatous, non infiltrated nodule. Full body work up revealed no metastases. Cutaneous biopsy concluded to trichoblastoma but failed to eliminate malignancy. After excision with secondary skin graft, histological examination confirmed the benignity with clear margins. There was no evidence of recurrence after a 5 year-follow-up period.

This case illustrates a rare clinical variant of trichoblastoma with an unusual important size. This can be misleading for malignancy, but the slowly progressive course of the tumour in our patient, together with histological benignity led to the correct diagnosis. This tumour is considered as a distinct entity by some authors.