Mucin 4: A Sensitive Diagnostic Marker for Pediatric MucoepidermoidCarcinoma

Abstract

Pediatric salivary gland-type neoplasms (SGTNs) pose a significant diagnostic problem due to histo-morphological heterogeneity. Previous reports have shown that Mucin 4 (MUC4) expression is associated with adult mucoepidermoid carcinoma (MEC). We hypothesize that MUC4 is also a sensitive marker for distinguishing MEC from other SGTNs in the pediatric population. A retrospective review of 74 SGTNs diagnosed between 1993–2015 at Children’s Hospital Los Angeles, Boston Children’s Hospital, and Rhode Island Hospital was performed. Hematoxylin and eosin-stained sections of 31 MECs were compared to 3 adenoid cystic carcinomas (AdCCs), 6 acinic cell carcinomas (AcCCs), 30 pleomorphic adenomas (PAs), 3 mammary analogue secretory carcinomas (MASCs), and one sialoblastoma (SB). Samples underwent immunohistochemical staining for MUC4, with expression score criteria: 0% positivity = 0, 1-10% = +, 11-50% = ++, 51-90% = +++, >90% = ++++. Ages of patients at time of tumor excision ranged from 2–19 years. All MECs were MUC4-positive, with 25 (80.65%) having an expression score ≥ +++. AdCCs and PAs demonstrated no to minimal MUC4-positivity. Subsets of AcCCs and MASCs were unexpectedly MUC4-positive. As a novel marker for pediatric MEC, MUC4’s sensitivity = 100%, specificity = 79.41%, positive predictive value = 75.86%, and negative predictive value = 100%.