Case 101 - Discussion

Uploaded: 2008-05-20, Updated: 2008-05-20

 

Microcystic Adnexal Carcinoma

CLINICAL FEATURES

  • Slow growing locally aggressive adnexal tumor.

  • Shows both eccrine and pilar differentiation, but it has been recently regarded as an apocrine tumour.

  • Usually on the upper lip of female or elsewhere on the face, may also occur in the axilla, extremities, genital skin, trunk and scalp.

GROSS FINDINGS

  • Skin colored indurated plaque or nodule.

MICROSCOPIC FINDINGS

  • Infiltrates in the dermis, subcutis and may extends into the underlying muscle.

  • Superficial Dermis:

    • Composed of numerous keratinous cysts.

    • Solid islands and strands of basaloid and squamous cells alternate with the cysts.

    • Ductal differentiation, focal microcalcification, clear cell changes, prominent lumina and arborizing tubules may be present.

  • Mid Dermis: prominent basaloid strand and ducts, diminished  keratinous cysts, may show focal sebaceous and follicular differentiation.

  • Deep Dermis: 

    • Schirrous appearance, smaller nests and strands of cells in a dense hyalinized stroma.

    • The epithelial elements are diminished to small clusters of 2 or 3 cells.

    • Cytologically the tumour cells are of uniform size. Mitotic figures are rarely seen.

SUBTYPES

  • Sclerosing sweat duct carcinoma or malignant syringoma: prominent glandular component.

DIFFERENTIAL DIAGNOSES

  • Desmoplastic trichoepithelioma, or syringomapapillary eccrine adenoma: no evidence of aggressive growth pattern or perineural spread. It is not possible to give a definitive diagnosis in shave or superficial punch biopsies.

  • Morpheic basal cell carcinoma: there is no lumen formation or zonation of the tumour.

IMMUNOHISTOCHEMISTRY AND SPECIAL STAINS

  • Tumor cells are positive for CEA, EMA, CK7

  • Stroma is CD34 negative.

TREATMENT AND PROGNOSIS

  • Mohs micrograph surgery is the current treatment of choice.

  • Local recurrence occurs in 50% cases.

REFERENCES

  • http://www.histopathology-india.net/MAC.htm

  • http://www.rcsed.ac.uk/journal/vol43_6/4360014.htm