Ultrastructure of spindle cell squamous carcinoma

Area of Science:

• Dermatopathology
• Oncology
• Surgical Pathology

Background:

• Atypical fibroxanthoma (AFX) and spindle cell squamous carcinoma (SCSC) are rare cutaneous neoplasms.
• Distinguishing between these entities can be challenging based on light microscopy alone.

Purpose of the Study:

• To evaluate the utility of electron microscopy in differentiating AFX from SCSC.
• To highlight the importance of ultrastructural analysis in problematic cutaneous tumor diagnoses.

Main Methods:

• Light microscopy of a skin lesion exhibiting features of AFX.
• Ultrastructural examination using electron microscopy.
• Comparison of histopathological and ultrastructural findings.

Main Results:

• Light microscopy suggested AFX, with a dermal lesion composed of spindle, polyhedral, and bizarre giant cells.
• Ultrastructure revealed abundant tonofilaments and desmosomes, indicative of epithelial origin, supporting SCSC.
• Electron microscopy provided critical diagnostic information not apparent on light microscopy.

Conclusions:

• Electron microscopy is essential for accurate diagnosis in cases of suspected AFX or SCSC.
• Ultrastructural findings of tonofilaments and desmosomes strongly favor a diagnosis of SCSC.
• Problematic cutaneous tumor diagnoses benefit significantly from the integration of electron microscopy.