Combined small cell carcinoma with giant cell carcinoma component of the lung: A case successfully diagnosed by computed tomography‑guided fine‑needle aspiration cytology

Abstract

Abstract. Combined small cell lung carcinoma (SCLC) is a rare variant of SCLC and is defined as a mixture of SCLC and non-SCLC components. Although any histopathological subtype may be present as a non-SCLC component, the presence of pleomorphic carcinoma components are extremely rare. The present report describes the first documented cytological features of combined SCLC with a giant cell carcinoma component. A 50-year-old Japanese female with a history of smoking presented with a mass lesion in the left lung. Computed tomography-guided fine-needle aspiration cytology and needle biopsy were performed, followed by a lobectomy. A Papanicolaou smear revealed the presence of two distinct neoplastic components in a necrotic background. One component was SCLC, which comprised small-sized neoplastic cells containing scant cytoplasm and round to oval nuclei with dispersed granular chromatin without nucleoli. The other component was giant cell carcinoma, which was composed of large-sized neoplastic cells containing irregular large hyperchromatic nuclei (approximately 7 to 10 times larger than those of SCLC). SCLC was demonstrated in the biopsy specimen, however no giant cell carcinoma component was present. Histopathological study of the lobectomy specimen verified a diagnosis of combined SCLC with giant cell carcinoma component. Both SCLC and giant cell carcinoma exhibit characteristic cytological features, therefore, albeit extremely rare, careful observation may lead to a correct diagnosis of combined SCLC in the cytological specimen. IntroductionCombined small cell lung carcinoma (SCLC) is categorized as a histopathological variant of SCLC, and defined as an admixture of SCLC and non-SCLC components (1). The incidence of combined SCLC is 0.2%-1.3% of the surgically resected primary lung cancers (2,3), and comprises up to 28% of the surgically resected SCLC cases (4). Adenocarcinoma and squamous cell carcinoma are the common components of non-SCLC (2-5). In the case series reported by Yamada et al adenocarcinoma is the most common histopathological subtype of the non-SCLC component (6/9 cases), followed by adenocarcinoma and squamous cell carcinoma (2 cases) and squamous cell carcinoma (1 case) (2). Any histopathological subtypes can be present as a non-SCLC component (1). However, the occurrence of a pleomorphic (giant cell) carcinoma component in combined SCLC is extremely rare (6-9). We have already reported on the clinical and histological characteristics of this case (10), and this report we described the detailed cytological features of combined SCLC with giant cell carcinoma component in order to draw attention to a potential cause of diagnostic error. Case reportA 50-year-old Japanese female was referred to Kansai Medical University Hospital because of an abnormal chest shadow, which had been detected by a chest X-ray examination at an out-patient clinic. She was a heavy smoker (30 cigarettes daily over 30 years). Chest computed tomography (CT) demonstrated a relatively well-circumscribed mass lesion, measuri...

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“…While only around 3-4% of SCLC patients have TSC1 alterations, a substantial fraction of SCLC patients possesses PI3K-Akt-mTOR pathway alterations (e.g., 9-10% patients with TSC2 alterations, 11-12% with PTEN alterations). Though cases of combined SCLC/giant cell carcinoma of the lung are rare in the clinic (Ebisu et al, 2018;Saito et al, 2017), our data suggest that these tumors may arise from dysregulation of the TSC1/TSC2-mTOR axis alongside RB/p53 loss-of-function.…”

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