Perianal fibroadenoma, case report

Area of Science:

• Dermatopathology
• Surgical Pathology
• Gynecologic Pathology

Background:

• Extramammary fibroadenomas are rare lesions originating from mammary-like anogenital sweat glands.
• These lesions are infrequently encountered in the anogenital region.

Observation:

• A 42-year-old woman presented with a 4-cm, slow-growing, well-circumscribed mass in the perianal region.
• The mass exhibited gross features of bulging, gray-white, and slightly lobulated appearance.
• Microscopic examination revealed a lesion identical to mammary fibroadenoma, with concurrent glandular and stromal elements.

Findings:

• The glandular component was lined by low columnar or cuboidal cells with apical snouts.
• Myoepithelial cells with smooth muscle actin and S-100 expression were present in the underlying layer.
• Immunohistochemistry showed epithelial reactivity for human milk fat globulin I, with 80% progesterone receptor and 60% estrogen receptor positivity.

Implications:

• This case underscores the importance of recognizing mammary-like glands in the anogenital region.
• These glands can potentially develop into various lesions, including fibroadenomas, fibrocystic disease, and rare malignancies.
• Increased awareness may aid in the diagnosis and management of these uncommon anogenital pathologies.