Case Report and Literature Review of Nodular Hiradenoma, a Rare Adnexal Tumor That Mimics Breast Carcinoma, in a 20-Year-Old Woman

Vanya Jaitly, MD; Richard Jahan-Tigh, MD, MS; Tatiana Belousova, MD; Hui Zhu, MD, PhD; Robert Brown, MD; Karan Saluja, MD


Lab Med. 2019;50(3):320-325. 

In This Article


Nodular hidradenomas are slow-growing adnexal tumors, which occur more often in women than men (2:1); they appear in the head and neck region at a mean age of 37.2 years.[2] In breast, tumors have been reported to occur more often in women, with a mean age of 47.9 years (range, 20.0–75.0 years) Table 1.

We reviewed 12 well-characterized cases of nodular hidradenoma/clear cell hidradenoma that occurred in the breast parenchyma, as yielded by our PubMed search; those cases are summarized in Table 1. Of these cases, 10 occurred in females and 2 in males. The lesions were present from 1.5 months to as long as 15 years, with size varying from 0.8 cm to as high as 8.0 cm. Most of these lesions were evaluated due to rapidly increasing size, ulceration, and/or pain.

In total, 7 of these 12 cases were clinically or radiologically suspicious for breast carcinoma.[2,4,5,7–9,11] Of those 7 cases, 4 were reported as malignant or suspicious for malignancy on initial fine needle aspiration (FNA) or core biopsy.[2,5,8,11] On excision, 11 of these 12 reported cases were diagnosed as benign hidradenoma, including 1 with atypical features, thereby highlighting that FNA or small core biopsy can yield misleading results for this uncommon tumor in breast tissue. One patient was diagnosed with hidradenoma with malignant transformation.[2]

Histologically, nodular hidradenomas are well-circumscribed benign neoplasms, occasionally rimmed by a fibrous pseudocapsule. Solid and cystic components may be present. The solid component typically shows 2 cell types, namely, large cells with eccentrically located nuclei and abundant clear cytoplasm due to glycogen accumulation and hence described as clear cell hidradenoma, and polyhedral cells with eosinophilic to amphophilic cytoplasm and round to oval vesicular nuclei. Cystic spaces are formed as a result of tumor degeneration and are filled by eosinophilic material. Squamoid and/or sebaceous differentiation, along with formation of ductular structures, has been reported.[13] The stroma is more commonly fibrous or hyalinized but myxoid (as observed in the present case), or chondroid stroma may be seen, in rare instances.[14] Also, in rare circumstances, these tumors can undergo malignant transformation characterized by necrosis, marked cytologic atypia, increased mitosis including atypical forms, infiltrative irregular borders, vascular invasion, perineural invasion, and/or distant metastasis.[13] In some cases, histologic testing may not accurately predict the clinical behavior.[7]

Nodular hidradenoma may have varied morphologic characteristics that mimic cutaneous and noncutaneous neoplasms, including primary breast neoplasms such as adenomyoepithelioma or invasive glycogen-rich clear cell carcinoma of breast tissue. The other differential diagnosis to consider includes metastasis to the skin/breast tissue from renal-cell carcinoma. The differential diagnosis and the morphologic and immunohistochemical features that differentiate them from nodular hidradenoma are discussed in Table 2.

In summary, hidradenoma is an uncommon skin adnexal tumor arising from the eccrine or apocrine glands. In breast tissue, it is a rare entity, and failure to identify its cytomorphologic features on FNA or core biopsy may lead to misdiagnosis. Hidradenoma should always be considered in the differential diagnosis of breast neoplasms in men and women, especially if the tumor shows clear cell changes.

The clue for a diagnosis of skin adnexal tumor is its superficial location. Nodular hidradenoma typically is located immediately beneath the skin, whereas breast carcinoma usually is deeply seated and only involves overlying skin at advanced stages. Also, an immunohistochemical panel, including CK5/6, p63, p40, ER, and PR may be helpful in differentiating hidradenoma from low- to intermediate-grade breast carcinoma (Table 2). Finally, a multidisciplinary approach is required to correctly diagnose these lesions for appropriate management.