Uterine Carcinosarcoma With an Adenosquamous Carcinoma and Low-Grade Endometrial Stromal Sarcoma-like Component: A Case Report.
Sung-Chul Lim
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Case in brief
A 55-year-old nulliparous woman presented with an endometrial mass involving the myometrium and endocervix. Biopsies showed atypical endometrial hyperplasia and cervical adenosquamous carcinoma. Hysterectomy demonstrated high-grade endometrioid carcinoma with extensive malignant squamous differentiation, transitioning morphologically into an infiltrative, LG-ESS-like stromal proliferation with lymphovascular invasion. The epithelial and stromal components had distinct immunophenotypes, while the transition showed shared p16 positivity and wild-type p53 staining. Findings favored a single biphasic neoplasm, although clonality was not molecularly confirmed. Despite postoperative concurrent chemoradiotherapy, the disease rapidly progressed with pelvic recurrence and enlarged metastatic lymph nodes.
What made this case unusual
The extensive morphological transition between adenosquamous carcinoma and an LG-ESS-like stromal component supported divergent differentiation within one biphasic tumor, rather than separate synchronous or collision tumors.
Diagnostic / clinical pearl
When carcinoma and an LG-ESS-like stromal proliferation coexist, assess for morphological continuity and compare immunophenotypes; these findings may support a biphasic neoplasm, but do not establish clonality without molecular confirmation.
Why it matters
The case broadens the described morphological spectrum of uterine carcinosarcoma and raises epithelial-mesenchymal transition as a possible explanation for an LG-ESS-like component.