The pleomorphic hyalinizing angiectatic tumour is a rare
tumour of uncertain lineage. It was first described in 1996 in a series
of 14 cases.
It is a
low-grade sarcoma which may recur locally. Metastasis has not been
recorded.
Site:
Mainly seen in the subcutaneous tissue
of the distal extremities
in adults.
Gross:
These are circumscribed or infiltrative lesion. Most tumours have a lobulated
appearance with a variegated, tan-brown hemorrhagic cut surface. Cystic
and myxoid changes may be present.
Microscopic features:
1. Clusters of
dilated thin-walled vessels with fibrinoid change of their wall with
superimposed thrombosis & occasionally hemosiderin-laden macrophage.
2. Intervening
stroma contain spindle shaped cells & bizarre polygonal multinucleate
cells. These multinucleate cells show marked nuclear pleomorphism,
hyperchromasia & frequently intranuclear inclusions. In rare cases psammomatous
calcifications may be noted.
3. A variable
inflammatory background mainly composed of lymphocytes, plasma
cells, and numerous mast cells.
Immunohistochemistry:
Multinucleate cells are CD34 positive (50% cases) but negative for
S-100 protein, actin and desmin.
Differential
diagnosis:
1. Ancient
Schwannoma (distinguished
from schwannomas by the
usual presence of infiltrative margins and
the absence of S-100 protein) ;
2. Melanotic
schwannoma (presence of hemosiderin, psammomatous calcifications, and
intranuclear inclusions).
3. Primary
cutaneous myxofibrosarcoma
(Primary
cutaneous myxofibrosarcoma mimicking pleomorphic hyalinizing angiectatic
tumor (PHAT): a potential diagnostic pitfall.Am
J Dermatopathol.
2005 Aug;27(4):322-6.)
4.
Hemosiderotic
fibrohistiocytic lipomatous lesion: PubMed
5. Some early cases may be
mistaken
for
spindle cell lipoma,
benign fibrous histiocytoma, or
nodular fasciitis.
Visit:
Myxoid Tumours of Soft Tissue
;
Soft
Tissue Tumours of Uncertain Differentiation ;
Neural tumours
;
Vascular tumours
;
Fibroblastic/Myofibroblastic tumours ;
Myofibroblastic tumours
;
Myogenic tumours
;
ChondroOsseous tumours
|