Because of the rarity of these hair germ tumors, classification is difficult and several schemes have been proposed. They proposed that all tumors with a follicular germinative cell are named Trichoblastoma. We have found in grouping all the above classifications that the GST is always described separately. Reports describing trichoblastomas have therefore been excluded from our survey. They all show a well demarcated tumor clearly differentiated as hair forming structures.
Immature hair appears as keratinous cysts surrounded by basophilic cells in an adenoid pattern.
Although GST has been described on the head, seven of the nine previously described cases have occurred on the lower body. The mean age of the published cases was 60 years with a range of 31-77 years, suggesting that the tumor may appear at any age, but shows a predilection for the older age group. Trichoepitheliomas in general are benign tumors, but in one of the only nine published cases of the giant solitary form recurrence after surgery has been described and an increased clinical awareness as well as follow up therefore seems indicated in this rare neoplasm. Differentiating neoplasms of Hair germ. J Clin Path.