# A Case of Pulmonary Basaloid Squamous Cell Carcinoma in a Non‐Smoking Female: Case Report and Literature Review

## TL;DR

A rare case of early-stage lung cancer in a non-smoking woman is reported, showing successful treatment and no recurrence after 18 months.

## Contribution

This is the first reported case of early-stage pulmonary basaloid squamous cell carcinoma in a non-smoking female.

## Key findings

- The patient, a non-smoking 67-year-old woman, was diagnosed with early-stage BSCC during routine health screening.
- Complete surgical resection led to a recurrence-free outcome 18 months postoperatively without adjuvant therapy.
- The case suggests BSCC can occur in non-smokers and at early stages, with potentially favorable outcomes.

## Abstract

Pulmonary basaloid squamous cell carcinoma (BSCC) is a rare, high‐grade subtype of lung squamous cell carcinoma. It predominantly affects elderly male smokers and is usually diagnosed at an advanced stage. Here, we report an early‐stage BSCC in a 67‐year‐old non‐smoking female identified during routine health screening. Chest CT revealed a 30‐mm mass in the right lower lobe. PET‐CT showed mild FDG uptake without lymph node or distant metastasis. Bronchoscopy confirmed malignancy, and thoracoscopic lobectomy with mediastinal lymph node dissection was performed. Gross pathology demonstrated a polypoid tumor protruding into the bronchial lumen. Histologically, the tumor exhibited solid basaloid nests with peripheral palisading and a high nuclear‐to‐cytoplasmic ratio. Immunohistochemistry showed strong p63 and CK5/6 positivity, with weak focal p40 expression in less than 20% of tumor cells. Ki‐67 labeling index was approximately 50%. Neuroendocrine and breast cancer markers were negative. Mosaic p53 positivity was observed, and no actionable mutations were identified via next‐generation sequencing. The final diagnosis was primary pulmonary BSCC (pT1cN0M0, Stage IA3). The patient remains recurrence‐free 18 months postoperatively without adjuvant therapy. A literature review of 11 representative reports revealed BSCC typically presents in older male smokers at later stages and carries a poor prognosis. This case highlights the potential for BSCC to occur in non‐smokers and at early stages, emphasizing the importance of a multidisciplinary diagnostic approach integrating histology, immunohistochemistry, and molecular data.

We report a rare case of early‐stage pulmonary basaloid squamous cell carcinoma (BSCC) in a non‐smoking female. The tumor was successfully treated with complete surgical resection, and the patient remains recurrence‐free after 18 months. This case highlights the potential for favorable outcomes in early‐detected BSCC among non‐smokers.