- Microcystic adnexal carcinoma is a low grade sweat gland carcinoma.
- Other names for this entity include malignant syringoma, and sclerosing sweat gland carcinoma.
- This tumor develops on the central face, including the eyelids.
- Eccrine carcinomas, including microcystic adnexal carcinoma, express follicular stem-cell markers, suggesting origin from the folliculosebaceous apocrine unit (Mahalingam, Am J Dermatopathol 2010).
- Around 700 cases of microcystic adnexal carcinoma have been reported in the literature.
- The initial six cases were all white patients, five were women and the average age was 44 years old (Goldstein, Cancer 1982).
- The tumor is rare in African Americans (Peterson, J Am Acad Dermatol 2001).
- In a Surveillance, Epidemiology and End Results (SEER) database analysis, 223 patients with MAC at all sites were identified indicating that it is a rare tumor (Yu, Am J Clin Oncol 2010).
- More than 50 cases of eyelid involvement with MAC have been described in the literature (Liyanage, Arch Ophthalmol 2010).
- Eyelid microcystic adnexal carcinoma can present as a lid nodule, usually yellow of flesh colored, as lid thickening or as progressive lid distortion.
- The course is insidious and symptoms may be present for several years before the diagnosis is made.
- The clinical appearance of a microcystic adnexal carcinoma is of an erythematous plaque or papule.
- A brownish-gray mass with ulceration is its typical appearance.
- The typical distribution is in sun exposed areas.
- Microcystic adnexal carcinoma is typically aggressive locally with invasion but infrequently disseminates beyond the primary site (Pugh, Head Neck 2012).
- Metastasis to regional lymphatics is rare.
- There is a case report of a primary orbital microcystic adnexal carcinoma which presented with diplopia and enophthalmos (Wu-Chen, J Neuroophthalmol 2011).
- Secondary orbital invasion by an eyelid MAC has been reported several times (Marshall, Orbit 2003; Hoppenreijs, Br J Ophthalmol 1997)
- Congenital microcystic adnexal carcinoma has been reported at non-ocular sites (Fu, Arch Dermatol 2011; Smart, Pediatr Dermatol 2011).
- In the SEER analysis described above only 1% of tumors proved to have regional lymph node involvement.
- There is a case report of MAC arising in the eyebrow, treated with primary excision and adjuvant radiotherapy (Ong, OPRS 2004).
Figure 1. Microcystic adnexal carcinoma. Image courtesy Mark J. Lucarelli, MD.
- The histopathology of microcystic adnexal carcinoma demonstrates islands of basaloid keratinocytes, some of which contain horn cysts and abortive follicles, embedded in a desmoplastic stroma.
- Ducts and gland-like structures lined by two-cell layers are present.
- The pathology is unusual in that deep invasion in the soft tissue, through the muscle layer, and perineural invasion are common but cytologic atypia and mitotic figures are rare.
- Immunohistochemistry can be helpful in differentiating between a morpheaform basal cell carcinoma, which characteristically is BerEP4 positive and microcystic adnexal carcinoma which characteristically is not (Seltheyer, J Cutan Pathol 2013).
- The monoclonal antibody BerEP4 is an epithelial marker that recognizes two glycopolypeptides (34 and 39) and also differentiates with a high degree of reliability between BCC and cutaneous squamous cell carcinoma.
Figure 2. Microcystic adnexal carcinoma pathology. Image courtesy Mark J. Lucarelli, MD.
Testing for staging, fundamental impairment
- There have been no studies on staging of eyelid MAC