SWI/SNF protein expression in anaplastic carcinomatous mural nodules of ovarian mucinous tumors.

Mural nodules arising in ovarian mucinous tumors are rare neoplasms encompassing anaplastic carcinoma, sarcoma-like mural nodules (SLMNs), and true sarcoma. Anaplastic carcinoma is characterized by pleomorphic, rhabdoid, and spindle cells, yet lacks specific prognostic markers. A previous report documented loss of SWI/SNF chromatin-remodeling complex proteins in anaplastic carcinoma, indicating a poor prognosis, but this finding has not been further explored. Fourteen cases of mural nodules (anaplastic carcinoma) arising in ovarian mucinous tumors are reviewed for clinical, morphological, and immunohistochemical (SMARCA4, SMARCA2, and SMARCB1) features. The median age was 42 years (range, 18-71 years). The median tumor size was 18 cm (range, 12-29 cm). Morphologically, 7 cases exhibited pleomorphic features, 3 exhibited sarcomatoid features, 3 exhibited rhabdoid features, and 1 case had mixed rhabdoid and sarcomatoid features. Immunohistochemically, five cases (36%) exhibited deficiency of at least one SWI/SNF subunit, including 2 with isolated loss of SMARCA2 (2/9), 1 with isolated loss of SMARCB1, and 2 with dual loss of SMARCA4/SMARCA2; no isolated loss of SMARCA4 was observed. Patients with loss of any SWI/SNF complex protein were younger than those with retained expression (median age, 34 vs. 52 years; p = 0.015). In univariate analysis, advanced FIGO stage (p = 0.018) and loss of SMARCA4 (p = 0.010) were associated with shorter overall survival (OS). Multivariate analysis confirmed that both advanced FIGO stage and loss of SMARCA4 were independent adverse prognostic factors. This study demonstrates the clinical utility of SWI/SNF complex evaluation, wherein SMARCA4 loss specifically pinpoints an aggressive tumor subset, providing a crucial tool for risk stratification.