Letters to the Editor
To the Editor:
Poroid hidradenoma (PH) is a rare eccrine neoplasm, described by Abenoza and Ackerman,1 and so-called because of its morphology intermediate between a poroma and a hidradenoma. As they are often cystic and superficially located, fine needle aspiration cytology has been useful in establishing a suspect of PH,2,3 but the diagnosis still relies on the histological examination and the findings of the typical cell population. We describe a case of PH with prominent papillary features, arising in the thigh of a 70-year-old white man who presented with a 2-cm reddish lesion. Clinically, the lesion was tender, localized in the deep dermis, and covered by normal-looking epidermis; it was surgically removed in fragments, with sparing of the epidermis, and sent for histological examination.
On light microscopy, it presented as a cystic lesion refilled by multiple papillae (Fig. 1), sometimes with large stalks, bordered by monomorphous, cytologically bland, poroid cells (Fig. 2), and larger eosinophilic cuticular cells showing evident ductular differentiation (Fig. 2, inset). At immunohistochemistry, the former were positive with cytokeratin AE1/AE3, whereas the latter reacted with cytokeratin 7, EMA (Fig. 3A), and, focally, CEA (Fig. 3B). Neither necrosis en masse nor atypia or increased mitotic activity was noted.
Our case fulfills morphological criteria for PH, as already described,4-9 namely, it is confined to the dermis, it has a prominent cystic component, and it is composed of a monomorphous population of either basaloid cells or large cuticular cells. Its immunohistochemical profile suggests that it is closely related to poroma,8,9 and it is in keeping with an eccrine derivation.
A quite unusual finding is the prominent papillary architecture, which expands the spectrum of growth patterns8; in the presence of papillary epithelial fronds, when dealing with an adnexal skin tumor, a diagnosis of PH should therefore be considered.
Simonetta Piana, MD
Elena Tagliavini, MD
Department of Pathology
Arcispedale Santa Maria Nuova
Reggio Emilia, Italy
1. Abenoza P, Ackerman AB. Neoplasm With Eccrine Differentiation
. Philadelphia, PA: Lea & Febiger; 1990:113-185, 311-350.
2. Layfield LJ, Mooney E. Fine needle aspiration cytology of poroid hidradenoma. Acta Cytol
3. Hoshida Y, Hanai J, Matsushita N, et al. Poroid hidradenoma: report of a case with cytological findings on fine needle aspiration. Acta Cytol
4. Requena L, Sanchez M. Poroid hidradenoma, a light microscopic and immunohistochemical study. Cutis
5. Ichioka S, Yamada A. A case of cystic dermal duct tumor corresponding to poroid hidradenoma. J Dermatol
6. Misago N, Kohda H. A single lesion demonstrating features of eccrine poroma and poroid hidradenoma. J Dermatol
7. Cho S, Kim J, Shin J, et al. Poroid hidradenoma. Int J Dermatol
8. Salem A, Abha M, Wedad H. Vulvar poroid hidradenoma. Am J Dermatol
9. Liu H, Chang Y, Chen C, et al. Histopathological and immunohistochemical studies of poroid hidradenoma. Arch Dermatol Res