Poorly differentiated non-keratinizing squamous cell carcinoma of the esophagus. A case report

Background: Background: Poorly differentiated non-keratinizing squamous cell carcinoma (PD-NK-SCC) of the esophagus is an uncommon histologic subtype characterized by basaloid morphology, minimal keratinization, and aggressive behavior. Case presentation: A 57-year-old male from Totonicapán, Guatemala, presented with progressive dysphagia and retrosternal pain. Endoscopy revealed an ulcerated lesion obstructing 90% of the esophageal lumen. Histopathology confirmed PD-NK-SCC, and CT imaging demonstrated wall thickening, mediastinal lymphadenopathy, and hepatic metastases. Discussion: PD-NK-SCC exhibits poor differentiation, high mitotic index, and necrosis, with immunohistochemical positivity for p40, p63, and CK5/6. Recent genomic studies highlight SWI/SNF complex alterations (SMARCB1/SMARCA4) and PD-L1 overexpression as markers of aggressiveness. Conclusion: PD-NK-SCC is a rare, aggressive malignancy requiring multidisciplinary diagnosis and treatment.

Keywords: Non-keratinizing squamous cell carcinoma, esophagus, SMARCB1, SWI/SNF, PD-L1, immunotherapy.