Pleomorphic Hyalinizing Angiectatic Tumor
Definition
- Mitotically inactive tumor composed of large bizarre cells with prominent ectatic vessels
Alternate / historical names
- PHAT
- Hemosiderotic fibrohistiocytic lipomatous lesion
- Proposed to be equivalent to early PHAT
Diagnostic criteria
- Large spindled and epithelioid cells
- Bizarre hyperchromatic nuclei
- Frequent intranuclear inclusions
- Abundant eosinophilic cytoplasm
- Frequently contain hemosiderin
- May contain pale cytoplasmic globules
- Prominent large thin walled vessels
- Frequently clustered
- Fibrin in and around vessel walls
- Stroma frequently hyalinized
- Microscopically infiltrative borders
- Predominantly subcutaneous, may involve dermis
- Dermal lesions may surround skin adnexae
- Mitotic figures very rare
- Early lesion pattern
- Short fascicles of bland spindled cells
- Hemosiderin in cells
- Infiltrates fat
- Aggregates around groups of small blood vessels
- Rare pleomorphic cells present
- Small blood vessels focally ectatic with fibrin
- Frequent myxoid matrix
- Early features may be seen adjacent to classic pattern
- Proposed to be equivalent to hemosiderotic fibrohistiocytic lipomatous lesion
- Short fascicles of bland spindled cells
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: September 15, 2007