Resected cytokeratin-negative small cell lung carcinoma

Area of Science:

• Oncology
• Pathology

Background:

• Small cell lung carcinoma (SCLC) is a neuroendocrine malignancy.
• SCLC typically expresses neuroendocrine markers and cytokeratins.
• Accurate SCLC diagnosis is crucial due to its aggressive nature and treatment response.

Observation:

• A rare pulmonary mass presented with SCLC morphology.
• The tumor lacked cytokeratin expression in biopsy and resection specimens.
• Extensive workup was performed to rule out other small round blue cell tumors, non-SCLC, and metastases.

Findings:

• The final diagnosis was SCLC, confirmed by positive neuroendocrine markers (synaptophysin, CD56).
• Ultrastructural analysis revealed neurosecretory granules.
• The key finding was the absence of cytokeratin expression in this SCLC case.

Implications:

• This case underscores the importance of considering SCLC even with atypical marker expression.
• Diagnostic challenges in SCLC require comprehensive immunohistochemical and ultrastructural evaluation.
• Understanding SCLC heterogeneity is vital for accurate diagnosis and patient management.