Hobnail pattern

Hobnail pattern (epithelioid angiosarcoma). H&E stain. (WC/Nephron)

Hobnail pattern (lactational changes). H&E stain. (WC/Nephron)

Hobnail pattern is a morphologic pattern that is seen in a number of contexts.

Definition

• Basement membrane area < area exposed to luminal surface.

Some considerations

Lung:

• Lung adenocarcinoma.
• Atypical adenomatous hyperplasia of the lung.

Breast:

• Lactational changes.

Gynecology:

• Clear cell carcinoma of the endometrium.

Kidney:

• Collecting duct carcinoma.
• Acquired cystic disease-associated renal cell carcinoma.
• Tubulocystic renal cell carcinoma.

Urinary bladder:

• Nephrogenic adenoma.

Other:

• Angiosarcoma.
• Endothelial cells in granulation tissue.
• Kimura disease.

See also

• Morphologic patterns.