Peripheral Squamous Cell Carcinoma of the Lung in a Smoker: A Radiological Case Report and Literature Review

Introduction

Lung cancer remains the leading cause of cancer-related mortality worldwide. Squamous cell carcinoma (SCC) traditionally arises from the central bronchi and is strongly linked to long-term smoking.1 However, an increasing number of SCCs are being identified peripherally within the lung parenchyma, a phenomenon attributed to changes in smoking habits and improved imaging detection.1-3 Peripheral squamous cell carcinoma (pSCC) can closely mimic adenocarcinoma on imaging due to its peripheral location and spiculated appearance.4,5 Recognition of this subtype is important, as it exhibits different histopathological characteristics, biological behaviour, and therapeutic implications.6,7

Case Report

A 76-year-old male chronic smoker presented with chronic cough, dyspnoea, and unintentional weight loss. Chest X-ray (posteroanterior view) revealed an ill-defined opacity in the right perihilar region, with thin atelectatic bands in both lower zones (Figure 1). Contrast-enhanced computed tomography (CT) of the chest showed an irregular, spiculated soft-tissue mass measuring 4.4 × 3.7 cm in the superior segment of the right lower lobe, along with multiple smaller spiculated nodules in the right upper and middle lobes on a background of centrilobular emphysema (Figure 2A–C). Mild right preparatracheal and subcarinal lymphadenopathy was noted, with no evidence of pleural effusion or chest wall invasion.

Figure 1: Chest X-ray (anteroposterior view) showing an illdefined opacity in the right perihilar region, with thin atelectatic linear bands in the lower zones of the right lung (white arrow).

Figure 2A–C: High-resolution computed tomography (HRCT) images — coronal, axial (A and B), and sagittal (C) views — showing a spiculated soft-tissue mass in the superior segment of the right lower lobe, with background centrilobular emphysema (white arrows).

Discussion

pSCC is an uncommon subtype of pulmonary SCC that arises from smaller bronchi or alveolar epithelium, unlike the more typical central SCC.3,4 Although most SCCs are centrally located, peripheral SCC should be considered in smokers presenting with spiculated peripheral pulmonary lesions, as failure to recognise this variant may delay accurate diagnosis and management. Radiologically, pSCC appears as a spiculated or lobulated peripheral mass, occasionally with cavitation or adjacent emphysema.5,6 Distinguishing pSCC from adenocarcinoma based solely on imaging is challenging.7 Histopathologically, pSCC demonstrates keratinisation and intercellular bridges, with immunohistochemistry (p40+, CK5/6+, TTF-1−, Napsin A−) being crucial for confirming squamous differentiation.8 Several studies and case series, including the one by Watanabe et al., have characterised the clinicopathologic and radiologic features of pSCC,3,4 highlighting the importance of awareness and accurate diagnosis to guide management and prognostication.

Declarations

• Ethics approval and consent to participate: Not required, as this report describes anonymised radiological data.

• Consent for publication: Not applicable, as no identifiable patient information is included.

• Competing interests: The authors declare no competing interests.

• Funding: None.

• Authors’ contributions: Dr. Sylvia Bedas Nsato conceived the case, performed imaging analysis, conducted the literature review, and drafted the manuscript. Supervisors and co-authors contributed to imaging interpretation, critical revision, and manuscript approval. All authors reviewed and approved the final manuscript.