Small cell carcinoma

Lung tumor
Other carcinoma
Small cell carcinoma

Author: Deepali Jain, M.D. (see Authors page)

Revised: 27 December 2016, last major update September 2012

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: small cell carcinoma[title] lung

Table of Contents

Cite this page: Small cell carcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lungtumorsmallcell.html. Accessed May 25th, 2018.

Definition / general

Also called oat cell carcinoma
10-20% all of lung carcinoma, 45,000 new cases per year in US
Usually men, median age 60 years, 99% occur in smokers, very aggressive with early mediastinal lymph node involvement
Apparently derived from primitive cells of basal bronchial epithelium with partial differentiation towards neuroendocrine cells
Associated with paraneoplastic syndromes due to production of ACTH (Cushing's syndrome), ADH (hyponatremia), calcitonin (hypocalcemia), gonadotropins (gynecomastia), parathyroid hormone (hyperparathyroidism), serotonin (carcinoid syndrome); also encephalomyelitis, Lambert-Eaton syndrome, sensory neuropathy
Two subtypes: pure or combined (Mod Pathol 2012;25:S18)
Biopsies often crushed
Cytology may be helpful
Diagnosis based on H&E, not the presence of neuroendocrine markers

Prognostic factors

Poor prognostic factors: elevated serum LDH, alkaline phosphatase, albumin, hemoglobin, white blood count

Treatment

Chemotherapy, radiation
Cure rates of 15-25% for limited disease
Most live 1 year
Preoperative chemotherapy and surgery if T1-2, N0-1, M0

Gross description

Usually central / hilar
White-tan, soft, friable, extensive necrosis
Peripheral nodules have fairly well-defined border and fleshy cut surface

Gross images

Images hosted on other servers:

Central tumor

Spreading along bronchi

Microscopic (histologic) description

Sheets, ribbons, clusters, rosettes or peripheral pallisading of small to medium sized (2-4x neutrophils) round / oval cells with minimal cytoplasm, salt and pepper chromatin without prominent clumps, hyperchromatic, indistinct nucleoli, nuclear molding, smudging, frequent mitotic figures
Azzopardi phenomena (basophilic nuclear chromatin spreading to wall of blood vessels), indistinct cell borders
Stroma is scanty, vascular, delicate
No glands, replacement of epithelium is less common than subepithelial growth
Necrosis and apoptotic debris are common
More cytoplasm is present in cells in metastases or resections than in small biopsies
May have larger cells with similar morphology, small mixtures of squamous cell carcinoma or adenocarcinoma (Am J Surg Pathol 2002;26:1184)
Rarely scattered giant cells, prominent nucleoli

Microscopic (histologic) images

Images hosted on other servers:

Flow, H&E, stains (not necessarily lung)

Virtual slides

Images hosted on other servers:

Various images

Positive stains

Pan-keratin (100%, dot like pattern), TTF1 (89%); also neuron specific enolase (77%), CD117 (75%, 50% after chemotherapy, Mod Pathol 2003;16:1041), chromogranin (58%, may be weak), synaptophysin (57%), calretinin (49%), thrombomodulin (27%), keratin5 (27%), CD57 / Leu7 (variable), gastrin releasing peptide, N-CAM / CD56, bcl-2 (variable)

Negative stains

CD3, CD20, CD45, CD99 / MIC2, pancreatic polypeptide, vimentin, mesothelin, p63

Flow cytometry description

CD56+ (neural cell adhesion molecule), CD45-, which differentiates from lymphoma (Arch Pathol Lab Med 2003;127:461)

Electron microscopy description

Occasional round, membrane bound, dense core neurosecretory granules, 100-200 nm in diameter
May have bundles of tonofibrils
May form glandular spaces

Differential diagnosis

Atypical carcinoid tumor: less nuclear atypia, < 20 mitotic figures per 10 HPF, no extensive necrosis, more intense neuroendocrine staining
Metastatic small cell carcinoma