RESIDENT CASE STUDIES

September 25, 2003: Case 5  

Table of Contents | List of Diagnoses | Case 1 | Case 2 | Case 3 | Case 4 | Case 5

An 81 year-old female presents with superior vena cava syndrome and a pleural effusion. Thoracentesis was performed for cytology

Discussion by Zach Ellis, MD

Small cell carcinoma is a highly malignant neoplasm of the bronchial epithelium with neuroendocrine features.

Incidence:  1/4 of lung malignancies

Gross Appearance: May be central or peripheral. Grows along the axis of the bronchus subepithelially.

Microscopic Appearance: 

• Cytologically there are 4 forms:
  • Pure small cell is composed of cells 1-2 times the size of lymphocytes
  • Intermediate size is up to 4 times the size of a lymphocyte
  • Combined small cell has foci of glandular or squamous differentiation
  • Mixed small and large cell contains large undifferentiated cells with abundant cytoplasm and prominant nucleoli
• In pure small cell, the cells have a high N/C ratio and are seen as single cells, loose clusters and form stacks of cells in single file
  • The nuclei are finely granular, pyknotic and round to angular with an irregular membrane and inconspicuous or absent nucleolus.

Diagnostic Criteria

• 1--2 times the size of a lymphocyte
• Single cells and loose clusters with nuclear molding
• Single file groups
• Finely granular, pyknotic, round to angular nuclei with irregular membrane and inconspicuous nucleolus
• High N/C ratio
• Mitoses and karyorrhexis

Immunostains:

• CD56, CK positive, weakly chromogranin positive

Differential Diagnosis:

• Lymphoma
• Reserve cell hyperplasia
• Poorly differantiated squamous cell carcinoma
• Poorly differentiated adenocarcinoma
• Neuroendocrine tumors

References:

1. Demay, RM. (1996). The Art and Science of Cytopathology. Chicago, IL: American Society for Clinical Pathology Press.
2. Stephen S Sternberg et al. (Eds): Diagnostic surgical pathology, Volume 1, 3rd edition. Lippincott William & Wilkins.