Donald T. King

Syringometaplasia: Mucinous and Squamous Variants

The eccrine sweat ducts are normally lined by cuboidal epithelial cells which may rarely undergo metaplasia, i.e. syringometaplasia. Two lesions were observed in which eccrine sweat ducts displayed the mucinous and squamous variants of syringometaplasia. The first lesion clinically and histologically appeared to be a plantar wart. Microscopically, it consisted of a central invagination surrounded by marked epidermal acanthosis and hyperkeratosis. The invagination was lined by keratinocytes admixed with mucin‐filled goblet cells. The mucin was positive by the Alcian blue (pH 2.5) and mucicarmine stains. Numerous eccrine sweat ducts led into the invagination and were focally lined by the mucin‐laden cells. Recognition of mucinous syringometaplasia is important since it may be confused with primary or metastatic adenocarcinoma of the skin. The second lesion occurred on the outer ear and was clinically believed to be chondrodermatitis nodularis helicis. Microscopically, there were many islands of atypical squamous cells within the papillary and reticular dermis. These epithelial islands represented squamous syringometaplasia since many contained central lumina with eosinophilic cuticles and blended with normal ductal structures. It is important not to confuse this metaplastic change with invasive squamous cell carcinoma. Squamous syringometaplasia may be analogous to necrotizing sialometaplasia, a recently described phenomenon which occurs in minor salivary glands.

Idiopathic calcinosis of scrotum

A forty-three-year-old man complained of painless, firm scrotal nodules which had first appeared at age sixteen. These were diagnosed clinically as multiple epidermoid inclusion cysts and were excised. Histologically they were composed of calcified, amorphous, granular material, characteristic of idiopathic calcinosis of the scrotum. This is a rare, benign condition without any recognized underlying metabolic abnormalities. The cause of idiopathic calcinosis of the scrotum is unknown, but we believe it is due to dystrophic calcification of dartoic muscles.

Bizarre cutaneous neurofibromas.

Bizarre cutaneous neurofibroma is an uncommon benign neoplasm. Microscopically, it is usually characterized by stellate and polyhedral cells embedded in a myxoid stroma, and less commonly by solid sheets of epithelioid cells. Cellular pleomorphism and mitotic figures are regular features and have resulted in erroneous diagnosis of malignancy. The mucinous material has the staining characteristics of a sulfated mucosubstance, probably chondroitin sulfate B. Terms previously applied to this lesion include nerve sheath myxoma. Pacinian neurofibroma, myxoid neurofibroma, and neurotheceoma.