Answer of Dermatopathology Case 9

Eccrine Spiradenoma

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Abstracts:

Adenoid cystic carcinoma-like pattern in spiradenoma and spiradenocylindroma: a rare feature in sporadic neoplasms and those associated with Brooke-Spieglersyndrome.Am J Dermatopathol. 2009 Oct;31(7):642-8.
Spiradenoma is a benign, morphologically well-defined cutaneous adnexal neoplasm that is closely related to cylindroma. We present the rare occurrence of adenoid cystic carcinoma (ACC)-like areas in 7 spiradenomas and 1 spiradenocylindroma, not described in the English literature to date. The ACC-like areas were a minor but significant component in all lesions and were usually multifocal and blended with the conventionally appearing parts of the neoplasms. The ACC-like areas weretypified by cribriform formations of epithelial cells concentrically arranged around gland-like spaces filled with mucin, homogeneous eosinophilic material, or granular basophilic material. In some neoplasms, only mucin occurred in these pseudoglandular structures, whereas in other cases, a combination of all 3 secretory products was encountered. Although well-developed bilayered glands witha demonstrable peripheral myoepithelial cell layer were not recognizable in the ACC-like areas, immunohistochemistry demonstrated myoepithelial differentiationin these portions of the tumors. When present in the ACC-like areas, ductalstructures manifested a rather squamoid lining, without a recognizable peripheral myoepithelial cell layer. It is concluded that the ACC-like pattern, although arare feature and of no clinical consequence, is a distinctive finding in a minority of cases and extends the morphological spectrum of spiradenoma and spiradenocylindroma occurring sporadically or in
the setting of Brooke-Spiegler syndrome. It represents a potential diagnostic pitfall, particularly in a limited biopsy specimen where the changes may be misdiagnosed as ACC.

Spiradenoma reminiscent of thymoma: report of a case and review of the literature. J Cutan Pathol. 2009 Feb;36(2):246-50. Epub 2008 Jul 21.
BACKGROUND: Spiradenoma (Sp) is a rare adnexal cutaneous tumor with a prominent vasculature. There are few reports in the literature suggesting that the majority of the cases contain perivascular spaces with numerous lymphocytes, a featurethat is characteristic in thymus neoplasms. However, there is little information available about the nature and maturity of the lymphocytes comprising these spaces. METHODS: We report a case of a Sp that presented as a palpable painlessmass in a 45-year-old woman and had histological similarities with thymomas. Furthermore, we compare these two entities in detail, discussing the differences and possible similarities between them. RESULTS: On histological grounds, thelesion consisted of epithelial lobules with prominent ductal differentiationadmixed with conspicuous perivascular spaces containing numerous lymphocytes. Immunohistochemical analysis showed that perivascular spaces contained mostly T lymphocytes (CD3 positive), which in contrast with those seen in most thymomas were mature (CD99, CD1a and Terminal deoxynucleotidyl transferase (Tdt) negative). A detailed comparison between Sps and thymomas shows that there exist several important clinicopathological and cytological differences between these two tumors. CONCLUSIONS: We suggest that the resemblance between Sps and thymomas is strictly architectural, and we raise some questions regarding the role of these perivascular spaces in tumor development.

Immunohistochemical differentiation of four benign eccrine tumors. J Cutan Pathol. 2009 Feb;36(2):190-6. Epub 2008 Jun 17.
Background: The histogenesis and differentiation of eccrine tumors, including cylindroma, poroma, spiradenoma and syringoma, remains controversial. This controversy may be because of sporadic and incomplete studies of these neoplasms. Methods: Ten examples each of normal eccrine structures and of four benign eccrine tumors are analyzed with antibodies to cytokeratin (CK) 7, CD34, CK6, CK10, smooth muscle actin (SMA) and CD10. These markers represent two different immunohistochemical stains for each part of the eccrine structure; CK7 and CD34 stain the secretory coil, CK6 and CK10 stain the straight duct and SMA and CD10 stain the myoepithelial cells. This redundancy in staining is performed on four benign eccrine tumors to better interpret the existing literature. Results: We find that CK7 is a sensitive marker for the secretory coil; both cylindromas and spiradenomas express CK7. We also find that CK6 is a marker for the inner ductal cells, while CK10 is a marker for the middle ductal cells; syringomas expressboth these markers. SMA appears to be a more specific marker for myoepithelialcells surrounding normal eccrine coils, and none of the studied tumors express SMA or CD10. Conclusions: Our studies suggest that syringomas are tumors of the eccrine duct, while cylindromas and spiradenomas are tumors of the secretory coil.