[187] Morphologic & Immunohistochemical Heterogeneity in Mucinous Carcinoma of Breast (MC)

Oleksandr N Kryvenko, Jiyoon Yoon, Javier Arias-Stella, Min W Lee, Dhananjay A Chitale. Henry Ford Hospital, Detroit, MI

Background: Pure MC (colloid), a special type of invasive ductal carcinoma (IDC), is associated with relatively favorable prognosis. However, reported incidence varies depending on histologic criteria used, so does the outcome. Our aim was to explore the morphologic & immunohistochemical spectrum of breast cancer with mucinous differentiation.
Design: From 2000 to 2011, we retrieved all the cases of breast cancer where the word 'mucinous' appeared in the final report. All the cases were reviewed & histologically classified based on cellularity & extracellular mucin content per published criteria as Type A MC (60-90% extracellular mucin in >90% of tumor & Type B-MC (<60% extracellular mucin in >90% of tumor). IDC-NOS with minor mucinous component were subtyped as mixed MC. Presence of intracytoplasmic mucin & morphologic features of neuroendocrine differentiation (NED) were recorded. 90 tumors were stained with antibodies against CD56, chromogranin, synaptophysin, estrogen & progesterone receptors, Her2neu, & Mib-1. Age, pathologic grade & stage were recorded. Chi-square & t-test were used for statistical analysis.
Results: There were 128 patients with 134 tumors. No statistical difference was observed between the subtypes in age (28-95 years; mean, 69.1) or pathologic stages (11 stage 1a, 39 – stage 1b, 34 stage 1c, 26 –stage2, 3 –stage 3). Average tumor size increased with cellularity (0.1-7.5 cm; mean 1.6 cm, statistically not significant). Lymph nodes were dissected in 101 cases (number:1-29; mean 4) & metastasis (LN+) were seen in 10 cases; all with larger primary tumor size (1.5cm vs 2.3cm, p=0.049), high Mib-1 index (16.2 vs 7.2, p=0.011), NED (60 vs 30%) & type B or mixed MC patterns (8/10). CD56 was positive in 15 cases. All tumors were positive for ER, 7 negative for progesterone. Intracytoplasmic mucin was most frequently present in type B MC.

Total MC typeMean size (cm)Synatophysin, (%)Chromogranin (%)Her2neu(%)Mib-1, meanLN+(%)
TypeA (n=70)1.425.522.934.53.8
TypeB (n=39)1.74336811.314.7
mixedMC (n=19)2.22315172121

Conclusions: We observed gain of aggressive histological & immunophenotypic features directly proportional to increasing cellularity & decreasing extracellular mucin content. With increasing cellularity there was larger tumor size, higher nuclear grade & proliferation index, frequent NED, Her2/neu positivity & increase chance of nodal metastasis. Therefore it is imperative to stratify MC using strict histologic criteria due to different clinical outcomes and tumors with conventional IDC should primary be called IDC with a note of focal mucinous differentiation.
Category: Breast

Monday, March 19, 2012 1:00 PM

Poster Session II # 43, Monday Afternoon


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