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SEER Inquiry System - Report
Produced: 04/22/2026 4:40 AM
Question 20210024
Inquiry Details
References:
WHO Class Female Genital Tumors. 4th edition
Question:
Primary Site--Vulva: What is the primary site of patient with an excision of a left vulvar cystic mass showing focal mammary-type ductal carcinoma in situ (DCIS) on 11/06/2020? See Discussion.
Discussion:
Final Pathologic Diagnosis:
Vulvar cyst, excision: Focal mammary-type ductal carcinoma in situ, intermediate grade, arising within cystically dilated duct (See Comment)
Size of DCIS: 0.7 CM.
Margins: Negative.
Comment
Sections demonstrate a cystically dilated duct. Focally, at the periphery of the duct, there is a neoplastic monomorphic proliferation of ductal cells with intermediate grade nuclei. No associated necrosis is identified. Immunostains for GATA-3 and estrogen receptor are strongly positive within the neoplastic cells, supporting origin from mammary-like epithelium. Immunostain for p63 demonstrates preservation of a basal layer around the dilated duct, including the region involved by DCIS. Immunostain for cytokeratin 5/6 shows loss of expression within the DCIS. No stromal invasion is identified. The cyst appears to be completely excised.
12/01/2020 post op visit with surgeon:
Ductal carcinoma in situ (DCIS) of the left vulva in an excised cystic lesion.
PLAN: I reviewed the pathologic findings from the excision of the left vulvar cyst. This appears to be a cystic lesion in the mammary line with focal DCIS. It was excised completely with negative margins. It would not warrant any additional treatment except expectant management.
Answer:
Code the primary site to vulva. Use text fields to record the details.
According to the WHO classification, several types of primary vulvar mammary-like carcinoma have been reported. It is rare and is thought to arise from specialized anogenital mammary-like glands within the vulva. It does not arise from ectopic breast tissue and is does not represent metastatic breast carcinoma.
