A 9-year old boy with a long history of frequently relapsing nephrotic syndrome was reviewed at the pediatric outpatient clinic soon after recent immigration from another country. One striking feature on physical examination was excessive hair growth. The hair growth was restricted to his back and existed of long, dark hairs. Upon further examination, there were no signs of sexual development, such as testicular enlargement or pubic hair.
Skin lesions on the upper thorax region
A. Zwagemaker & M.J.S. Oosterveld
Hypertrichosis (correct answer): Our patient suffers from hypertrichosis, as the hair growth is limited to his back and not apparent in androgen-dependent areas (pubic regions or arm pits). Hypertrichosis is defined as excessive hair growth unrelated to androgen levels. It can be familial, idiopathic, metabolic or medication induced as was the case in our patient. Hypertrichosis is a common side effect of cyclosporine (1-10%) and phenytoin, and to a lesser extent of prednisone (0.1-1%). Metabolic causes include hypothyroidism and porphyria.
Hirsutism: Unlike hypertrichosis, hirsutism is androgen-mediated hair growth and is therefore a sign of underlying androgen excess. Concurrent symptoms may be acne and male-pattern alopecia. Causes include polycystic ovary syndrome and Cushing’s syndrome. Our patient has a mild “buffalo hump” suggestive of Cushing’s syndrome. However, the absence of androgen-driven hair growth argues against Cushing’s syndrome and both the hypertrichosis and buffalo hump can be ascribed to chronic steroid use.
Lanugo: Similar to hypertrichosis, lanugo hair is androgen-independent and may cover the whole body. However, lanugo hairs are soft, mostly unpigmented and normally apparent in neonates. Lanugo hair is a pathological sign of malnutrition in children or adults.
Premature pubarche: Our patient does not have any pubic hair. Premature pubarche in boys refers to the sole appearance of sexual pubic hair in the absence of testicular enlargement.