Syringoid eccrine carcinoma: a clinicopathological and immunohistochemical study of four cases

Syringoid eccrine carcinoma (SEC) is a rare malignant adnexal tumour with variable presentations.

To examine the clinicopathological and immunohistochemical features of SEC.

Four cases were reviewed by three dermatopathologists and the immunohistochemical profile was examined using antibodies against CK5/6, CK7, CK14, CK20, LMWK, HMWK, EMA, mCEA, p63, ER, PR, AR, S-100 and Ber-EP4.

The cases occurred in two men and two women, ranging in age from 61 to 87 years (mean 68.5). Two of the lesions were from the face and two from the trunk. All four lesions were composed of an atypical infiltrative mass with syringoma-like tadpole morphology with ductular differentiation and prominent desmoplasia. Three cases demonstrated perineural invasion and two had positive lymph node metastases. Immunostaining was variable. Immunohistochemistry positivity was as follows: three out of four cases were positive for CK5/6, CK7 (2/4), CK14 (1/3), CK20 (0/2), HMWK (0/2), LMWK (1/2), EMA (3/4), mCEA (4/4), p63 (2/3), ER (2/3), PR (1/2), AR (0/3), S-100 (0/3) and Ber-EP4 (2/2).

SEC can present on the trunk and are not limited to the head and neck region. In addition to syringoma-like tadpole structures and glandular differentiation, these tumours can also exhibit squamoid and cribriform growth patterns. Immunostaining in SEC is variable and this variability is believed to stem from this tumour's ability to differentiate along multiple routes, including sweat secretory and/or ductal differentiation.