Mammographic and ultrasound findings in poroid hidradenoma of the breast mimicking intraductal papilloma and papillary carcinoma: A case report

RATIONALE: Poroid hidradenoma (PH) is a rare variant of benign sweat gland neoplasm without connection to the epidermis. This tumor presents clinically as a solitary lesion with a cystic component located in the subcutaneous layer abutting the skin. On ultrasound, it appears as a circumscribed complex cystic and solid mass abutting the dermis. The occurrence of PH in the breast is very rare. Its features overlap with intraductal papilloma and papillary carcinoma. PATIENT CONCERNS: A 66-year-old woman presented with a palpable lump in her right breast. DIAGNOSES: Clinical examination revealed dark bluish dome-shaped nodule which presented as circumscribed round isodense mass on mammography and oval complex cystic and solid mass abutting the dermis on ultrasound. Clinically, a papillary neoplasm was suspected. INTERVENTIONS: The patient underwent En bloc surgical excision including the overlying epidermis and the surrounding adipose tissue to prevent recurrence. OUTCOMES: A well-demarcated, non-encapsulated grayish white mass composed of a partly solid and partly cystic area was completely removed and histopathologically confirmed as PH. At the 12-month follow-up, no recurrence was evident. LESSONS: PH should be considered in the differential diagnosis of a slowly growing breast mass that is bluish, cystic, and solid and abuts the dermis.