A Case of Fibrous Hamartoma of Infancy with Hypertrichosis on the Axilla

Fibrous hamartoma of infancy is a rare benign lesion that presents as a solitary, painless, flesh-colored, subcutaneous mass. Most of these lesions occur in the axillary region, the upper arm, the upper trunk, the inguinal area and the external genital area. The lesion histologically consists of three different components in varying proportions: well-defined fibrous trabeculae, primitive mesenchyme and, mature adipose tissue. Overlying skin changes are uncommon, including alternations in pigmentation, eccrine gland hyperplasia and increased hair. To the best of our knowledge, only 6 cases of fibrous hamartoma of infancy with hypertrichosis have been reported. In these six cases, the lesions were located on the buttocks and back, which were non-predilection sites. We report the first case of fibrous hamartoma of infancy with hypertrichosis on the axilla, which is known as a predilection site.