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Review
. 2021 Feb 16;13(4):820.
doi: 10.3390/cancers13040820.

Pathology and Classification of SCLC

Maria Gabriela Raso  1 , Neus Bota-Rabassedas  1 , Ignacio I Wistuba  1
Affiliations
Review

Pathology and Classification of SCLC

Maria Gabriela Raso et al. Cancers (Basel). .

Abstract

Lung cancer is consistently the leading cause of cancer-related death worldwide, and it ranks as the second most frequent type of new cancer cases diagnosed in the United States, both in males and females. One subtype of lung cancer, small cell lung carcinoma (SCLC), is an aggressive, poorly differentiated, and high-grade neuroendocrine carcinoma that accounts for 13% of all lung carcinomas. SCLC is the most frequent neuroendocrine lung tumor, and it is commonly presented as an advanced stage disease in heavy smokers. Due to its clinical presentation, it is typically diagnosed in small biopsies or cytology specimens, with routine immunostaining only. However, immunohistochemistry markers are extremely valuable in demonstrating neuroendocrine features of SCLC and supporting its differential diagnosis. The 2015 WHO classification grouped all pulmonary neuroendocrine carcinomas in one category and maintained the SCLC combined variant that was previously recognized. In this review, we explore multiple aspects of the pathologic features of this entity, as well as clinically relevant immunohistochemistry markers expression and its molecular characteristics. In addition, we will focus on characteristics of the tumor microenvironment, and the latest pathogenesis findings to better understand the new therapeutic options in the current era of personalized therapy.

Keywords: biology of SCLC; immune-checkpoint inhibitors in SCLC; pathology and classification of SCLC.

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Conflict of interest statement

I.I.W. receives research funding from Genentech, Oncoplex, HTG Molecular, DepArray, Merck, Bristol-Myers Squibb, Medimmune, Adaptive, Adaptimmune, EMD Serono, Pfizer, Takeda, Amgen, Karus, Johnson & Johnson, Bayer, Iovance, 4D, Novartis, and Akoya. I.I.W. sits on the advisory board of the following companies: Genentech/Roche, Bayer, Bristol-Myers Squibb, Astra Zeneca/Medimmune, Pfizer, HTG Molecular, Asuragen, Merck, GlaxoSmithKline, Guardant Health, Oncocyte, and MSD. The funders had no role in the writing of the manuscript.

Figures

Figure 1
Figure 1
Small cell lung carcinoma (SCLC) cytological and histological characteristics. (a,b) High power field view of SCLC in cellular aspirates. Loosely arranged small blue cells with scant cytoplasm and fine chromatin features (arrow).
Figure 2
Figure 2
Small cell lung carcinoma (SCLC) cytological and histological characteristics. High power field view of a formalin fixed paraffin embedded tissue H&E stained slide showing in (a). sheets of small cells with scant cytoplasm and nuclear molding and (b). Sheets of tightly packed small cells and intratumoral necrosis.
Figure 3
Figure 3
Chromatin smearing “crush artifact”. High magnification showing Small cell lung carcinoma (SCLC) with extensive chromatin smearing “crush artifact”.
Figure 4
Figure 4
Azzopardi phenomenon. High magnification showing Small cell lung carcinoma (SCLC) with basophilic nuclear debris encrustation of the blood vessel wall (arrow).
See this image and copyright information in PMC

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