APOCRINE HIDROCYSTOMA
The apocrine hidrocystoma (AHC) and the proliferative counterpart, the apocrine cystadenoma, occur most frequently on the face. Although many are flesh colored, occasional examples are very dark and may be confused with a melanocytic lesion clinically. Actually, the clinician who sent in the specimen below thought it would be a nodular melanoma. The cyst fluid may be straw colored or quite dark or anything in between. The dark bluish gray gross appearance of some AHC's is a manifestation of the color of the cyst fluid and the optical phenomenum similar to that occuring in 'blue dome' cysts of the breast.

AHC's may be unilocular or multilocular, and the prototypic example is lined by a single layer of epithelium having apocrine characteristics. A layer of thin, inconspicuous myoepithelial cells is found beneath the lining epithelium. The epithelium in some examples is so flattened that the distinction between apocrine morphology and eccrine morphology is difficult or impossible. Apocrine snouts are diagnostic in this setting. Decapitation secretion, granules that are positive for the periodic acid-Schiff reaction, and brown, lipofuchsin granules are variably present. Lipofuchsin granules are stated to occur in the apices of the epithelial cells but  may be located anywhere in the cytoplasm of the apocrine cells. Lipofuchsin granules are autofluorescent  and variably positive in PAS and acid-fast (Kinyoun or Ziehl-Neelsen stains) stained sections.


This was a dark lesion from the cheek of a 39 year old male:
 
Scan power view showing multiple cystic areas. The fluid does not contain pigment granules though the fluid was dark.
A high power view of the linings of two of the cysts. A few brown,  lipofuchsin pigment granules (PG) are in the basilar part of the epithelium. There is a suggestion of pigmented material in the apices of other cells. Apocrine snouts are prominent. 

Click on your browser's 'Back' button to return to the previous page.