SYRINGOMATOUS CHANGES OF ECCRINE SWEAT-DUCTS ASSOCIATED WITH PRURIGO NODULARIS

Alteration of the eccrine sweat ducts has been observed in association with an expanding list of conditions. To our knowledge, this phenomen on has not been described in association with prurigo nodularis. We re port on a 68-year-old man with a fibrotic nodule on his chin that had been present for 8 months. Microscopic examination showed marked hyper keratosis overlying the epithelium. There was also hypergranulosis, ma rked acanthosis, and irregular elongation of the rete ridges. These fi ndings were consistent with prurigo nodularis. In addition, within the reticular dermis, there was marked fibrosis and a proliferation of ec crine sweat ducts. The ducts were enlarged and varied from cystic to r arely solid structures. Rare ducts formed a tadpole-shaped tail, remin iscent of syringoma. The duct lining demonstrated a multilayered epith elium that was three to eight cells thick, yielding a solid component to some of the cysts. Although some of these features were similar to those of a syringoma, the typical small gland proliferation and bilaye red lining was not evident. This case (a) demonstrates the association of syringomatous changes of eccrine sweat ducts with yet another cond ition, prurigo nodularis, and (b) emphasizes the importance of differe ntiating this benign reactive process from the malignant neoplasms mic rocystic adnexal carcinoma and squamous cell carcinoma.