Spiroadenoma with partial cystic degeneration: presentation of a case

Abstract

Abstract: 

Spiroadenoma is a benign sweat gland neoplasm originally described by Kersting and Helwig. It generally appears in adults as a single, sometimes painful or tender nodule located on the head, neck or trunk. It is made up of one or more well-circumscribed lobes in the dermis composed of a double epithelial population with focal ductal differentiation and intratumoral lymphocytes.  It is accompanied by an edematous stroma with blood and lymphatic vessels. There are other forms of clinical presentation and histopathological variants of this tumor, including a cystic form.

A 50-year-old man consulted for a two-year evolution of a nodule on the left forearm. We received a 3 cm nodule referred as a "cystic lesion" covered by skin. On section it was solid with cystic areas containing bloody fluid. It was processed with routine techniques and stained with hematoxylin/eosin. Microscopy: well defined dermal proliferation of two types of epithelial cells without atypia arranged in cords and with ductal differentiation. Between both components there was a variable number of lymphocytes. The stroma was not very evident in the solid areas but in other sectors it was distended by abundant edema forming cavities with amorphous eosinophilic material, fibrin and red blood cells. Some cavities even showed signs of organization and old bleeding. The surgical boundary was free.  

There are multiple clinical presentations and morphological variations of spiroadenoma. The cystic form can be explained by cystic distention of the perivascular spaces of the stroma, which are a typical feature of this tumor. They correspond to spaces of variable size around one or more blood vessels and are delimited by a palisade of tumor epithelial cells, findings similar to those seen in thymomas. They contain a variable number of lymphocytes and could participate in their transit to the tumor. They may also contain proteinaceous material or erythrocytes and form large cavities in the tumor which can manifest clinically as a cystic lesion similar to the case we present.