[326] Clinicopathologic Evaluation of Papillary Carcinoma of the Breast

C Wynveen, M Akram, E Brzostowski, T Nehhozina, J Goldberg, U Rudloff, K VanZee, L Norton, E Brogi. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Intracystic Papillary Carcinoma (IPC) of the breast is traditionally regarded as a variant of ductal carcinoma in situ (DCIS). Recently, Collins and colleagues (Am J Surg Pathol 2006) reported lack of myoepithelium (MEC) in 22 IPCs and suggested that this tumor represents an encapsulated invasive carcinoma. Although most studies show that IPC is an indolent neoplasm, reports of lymph node (LN) and distant metastases exist. We evaluated morphology, immunoprofile and clinical follow-up of IPC to address some of these questions.
Design: We searched our files for slides and blocks of IPC diagnosed between January 1990 and June 2008. One pathologist (C.W.) reviewed all available material and assessed tumor morphology, including presence and extent of associated invasive carcinoma (IC). We performed immunoperoxidase stains for MEC (calponin, p63 and smooth muscle myosin heavy chain) on all available tumor blocks, and tested ER, PR and Her2 on one. Clinical data was obtained from medical records.
Results: We identified 23 IPCs from 22 patients (21 women, 1 man), including one with two distinct IPCs. Median age at diagnosis was 70 years (range 47-83), and median tumor size 1.7 cm (range 0.6-5.0). Thirteen tumors involved the right breast, ten the left. The original diagnoses ranged from IC (3), in situ (8), and in situ and IC (12). Seven cases were pure IPC, 4 IPC+microinvasion (MI), 12 IPC+IC>2 mm. All IC>2 mm were ductal, well (n=9) or moderately differentiated (n=3); IC was cribriform in one case and mucinous in another. IPCs were predominantly papillary in 17 cases, cribriform in 2 and solid in 4. Associated DCIS was less frequent in pure IPC and IPC+MI (4/11; 36%) than in IPC+IC> 2mm (10/12; 83%). All tumors were ER(+), Her2(-); 20/23 were PR(+). Nuclear positivity for p63 highlighted focal residual MEC at the periphery of IPC in 2/23 cases. Three patients underwent mastectomy and 19 lumpectomy. None of 17 patients with LN evaluation (13 sentinel LN and 4 axillary dissection) had metastasis. Two pure IPCs recurred with the same morphology 2 and 10 years after the initial diagnosis.
Conclusions: Our results confirm that most IPCs lack MEC, suggesting an invasive process. Nonetheless, focal residual MEC were present in two cases, raising the possibility that IPC may represent a spectrum of progression from in situ to IC. Our follow-up data confirms that LN involvement is uncommon, and that these tumors have a good prognosis, but can locally recur.
Category: Breast

Monday, March 9, 2009 9:00 AM

Platform Session: Section B, Monday Morning