Eccrine syringofibroadenoma (ESFA) is a rare eccrine tumor. We report the case of a 70-year-old woman who had presented a pincer nail deformity on the toes for 55 years and a left painless subungual tumor for 2 years. Histologic examination revealed branching anastomosing strands of epithelial cells with ductal structures in a fibrovascular stroma. The luminal cells showed positive staining for carcinoembryonic antigen, as in acrosyringeal cells and cells of dermal ducts. To our knowledge, our case is the first with a subungual location. In the context of chronic trauma due to a pincer nail, it may be classified in the reactive subtype recently described.

Immunohistochemical analysis of cytokeratin expression in reactive eccrine syringofibroadenoma-like lesion: a comparative study with eccrine syringofibroadenoma.J Cutan Pathol. 2000 Apr;27(4):164-8.

In addition to solitary eccrine syringofibroadenoma (ESFA), there is another type of ESFA which is associated with underlying dermatoses (reactive ESFA-like lesion). Five lesions in 4 patients of reactive ESFA-like lesion were analyzed by an immunohistochemical method using 13 kinds of anti-cytokeratin (CK) antibodies. Two cases of solitary ESFA were also studied by the same procedure for comparison. Suprabasal staining pattern of AE1 and MNF116, which stain CKs 6, 16 and 17, markers of hyperproliferative state, was observed diffusely in 5 lesions of reactive ESFA-like lesions except for focal negative staining in one case, and was observed focally in one case of solitary ESFA. Furthermore, differentiation-specific cytokeratin expression was reduced in 3 of 5 lesions of reactive ESFA-like lesions. Both ESFA and reactive ESFA showed basically similar immunoreactivity suggesting differentiation toward the dermal duct. The above slight difference in immunoreactivity between both lesions may be explained due to inflammatory infiltrates associated with underlying dermatoses.

Eccrine syringofibroadenoma: case report and review of the literature. J Eur Acad Dermatol Venereol. 2001 Mar;15(2):147-9.

Eccrine syringofibroadenoma (ESFA) is a rare disorder that shows differentiation toward eccrine sweat apparatus. There is a controversy concerning the pathogenesis and differentiation of this tumour. We report a case of ESFA in a 63-year-old Japanese man. We review the literature presenting a classification, including a newly reported subtype. Clinically and pathogenically, ESFA is probably a group of heterogeneous disorders.