Calcific neck mass in an adolescent girl. Pilomatricoma with heterotopic ossification.

Abstract

Ahealthyadolescentgirlpresented for evaluationof a lump in the right side of her neck. She reported that it had been slowly enlarging since she first noticed it 3 years previously. The mass was painless. She had not experienced dysphagia, voice changes, skin changes, or drainage. There was no history of trauma to this region. She had a remote history of adenotonsillectomy and currently used tobacco. Examination of the neck revealed a 2-cm, hard, irregular, superficial, mobile mass located just lateral to midline and just deep to the skin without erythema or induration of the surrounding tissue. Deep palpation elicited tenderness, and overlying skin dimpling was noted. There was no lymphadenopathy or thyromegaly, and findings from the examination were otherwise unremarkable. Thepatientagreedtoundergosurgical excision.A2 × 0.8 × 0.7cm calcified mass was excised after mobilization of its attachments to the platysma muscle. The gross specimen was tannish yellow in colorandhardwithcalcifications (Figure,A).Histopathologicexamination revealedawell-circumscribed lesionofheterogenousappearance (Figure, B, ×12.5magnification). Highermagnification revealed islands of basaloid and shadow cells and associated trabecular bone containing entrapped osteocytes (Figure, C, ×100 magnification). Giant cellswere visible at the periphery of the basaloid cellmatrix. What is your diagnosis? A