[178] Significance of Myoepithelial Cell Layer around Ducts with Papillary Ductal Epithelial Neoplasia (DIN 1-3) (Papillary Ductal Carcinoma In-Situ, DCIS 1-3)

Malini Harigopal, Christopher Flynn, Priyanka Karam, Maria Orsaria, Fattaneh A Tavassoli. Yale University School of Medicine, New Haven, CT

Background: While persistence of myoepithelial cells around a duct with papillary DIN 1-3 (PDIN = Papillary DCIS) is helpful in excluding an invasion, the significance of its absence in this setting is controversial. Furthermore, when the PDIN 1-3 is associated with adjacent conventional invasive carcinoma (IC), the size and stage of the carcinoma could vary substantially depending on whether the papillary component is interpreted as invasive or intraepithelial.
Design: In a retrospective search of the pathology database at our institution for all PDIN 1-3 (Papillary DCIS) with excisional biopsy between 2001 to 2011, a total of 50 (PDIN, solid), 2 (PDIN, intracystic), 12 PDIN with associated IC were identified and reviewed. 27 low grade PDIN of solid and intracystic types with or without associated IC were further evaluated with 3 ME (p63, calponin and CD10) and 2 basement membrane markers (collagen IV & laminin).
Results: All low grade PDIN (22) showed absence of ME (>90%) within the intraluminal papillary fronds and focal or discontinuous ME cell around the duct; BM markers showed retention of BM around distended ducts with PDIN. PDIN with associated IC (n = 5) showed complete absence of ME cells around the distended ducts with PDIN. BM was present around PDIN, but absent around foci of IC. The size of the PDIN varied from 3 mm to 2.7 cm, while the adjacent invasive carcinoma (IC) varied from <0.1 to 1.3 cm. Only one of the 22 cases had nodal metastases, this case had IC.
Conclusions: The majority of papillary DIN 1-3 is non-invasive with an expansile growth in distended ducts. The IC associated with PDIN (5) was a conventional IDC (n = 4) or mucinous (n=1). The absence of ME cells around ducts in the absence of typical IC architecture is not an indication of an invasive carcinoma. Ultimately, the prudent use of both histologic criteria and IHC in papillary DIN 1-3 with or without associated IC is critical to avoid overstaging and overtreatment. Papillary DIN 1-3 lesions devoid of any ME cells have excellent prognosis similar to DIN 1-3 (DCIS, grades 1-3).
Category: Breast

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 15, Wednesday Morning


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