Epithelioid cell lesions

An tumour with an epithelioid morphology (epithelioid sarcoma). H&E stain.

Epithelioid cell lesions are very common in pathology. Malignant epithelioid lesions are most often carcinomas... but may be a large number different tumours.

Classification

Broadly, epithelioid lesions are split into:

• Small round cell tumours.
• Large epithelioid tumours.

General differential diagnosis

A short DDx:

• Carcinoma (primary and metastatic).
• Malignant melanoma.
• Sarcoma.

Epithelioid sarcomas

All rules are made to be broken... some epithelioid lesions are sarcomas:

• Epithelioid sarcoma.
• Epithelioid angiosarcoma.
• Alveolar soft part sarcoma.
• Rhabdoid tumour.

Others:

• Clear cell sarcoma.
• Epithelioid gastrointestinal stromal tumour.
• Synovial sarcoma, primitive round cell type.
• Sarcomas in the small round cell tumours group, e.g. Ewing sarcoma.

Note:

• An exhaustive DDx is found in large epithelioid tumours and small round cell tumours.

See also

• Spindle cell lesions.
• Basics.
• Pleomorphic tumours.
• Large epithelioid tumours.