A 47-year-old woman presented with acute intestinal obstruction. Contrast-enhanced computed tomography suggested an ileocecal stricture, and an emergency right hemicolectomy was performed. Grossly, an annular stricture with intact mucosa was identified. Histology showed diffuse mural infiltration by discohesive tumor cells arranged in cords and single-file strands with mucosal sparing, favoring metastatic invasive lobular carcinoma (ILC). Targeted review revealed a neglected right-breast mass, core biopsy showed hormone-receptor-positive, human epidermal growth factor 2-negative carcinoma with lobular morphology, and low Ki-67. Immunohistochemistry demonstrated breast lineage (GATA3-positive) and aberrant/retained E-cadherin with p120 catenin cytoplasmic redistribution (with residual membranous staining) and loss of membranous β-catenin, supporting ILC with aberrant E-cadherin expression rather than ductal carcinoma. The patient was referred for systemic therapy. This case illustrates a “double deception,” a clinical mimic of ileocaecal tuberculosis or primary colonic carcinoma and a pathological pitfall due to deceptively retained E-cadherin staining, underscoring the risk of misdiagnosis and the critical importance of careful microscopic morphology and a high index of suspicion, supported by a morphology-first, panel-based immunohistochemical approach (E-cadherin/p120/β-catenin) when E-cadherin expression is aberrant.
Nehil et al. (Fri,) studied this question.
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