Subepidermal Calcified Nodule in a Child With Neurofibromatosis Type 1.

Calcinosis cutis (CC) is characterized by calcium deposition in the subcutaneous tissues. Subepidermal calcified nodule (SCN) is a variant of idiopathic calcinosis most commonly seen in the head and neck region of children and adolescents as a single, small, painless, yellow-white papule. A 13-year-old boy with a medical history of neurofibromatosis type 1 (NF1) presented with a firm 0.3 cm white papule in the lower eyelid. He also had neurofibromas of the left forearm and spinal cord, and a malignant peripheral nerve sheath tumor of the right forearm. The eyelid lesion showed hyperkeratotic epidermis, papillomatosis, and elongated rete ridges, with a radial arrangement at the periphery of the well-circumscribed lesion comprising many dystrophic calcifications, histiocytes, and foreign body giant cell reactions. To our knowledge, this is the first case of SCN reported in the context of NF1 or any other systemic disease in the English literature. Although a coincidence is likely, rare observations of the parathyroid gland and calcium metabolism disorders in association with NF1 may provide an explanation that requires further investigation.