http://www.histopathology-india.net/SoftTissuePath.htm

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

Abstracts:

Pleomorphic hyalinizing angiectatic tumor of soft parts: case report and literature review.J Cutan Pathol. 2006 May;33(5):361-4.

Pleomorphic hyalinizing angiectatic tumor of soft parts: ultrastructural analysis of a case with original features.Ultrastruct Pathol. 2006 Jan-Feb;30(1):59-64.

Pleomorphic hyalinizing angiectatic tumor: analysis of 41 cases supporting evolution from a distinctive precursor lesion. Am J Surg Pathol. 2004 Nov;28(11):1417-25.

Pleomorphic hyalinizing angiectatic tumor of soft parts: report of a case and review of the literature.J Dermatol. 2004 May;31(5):419-23.

Pleomorphic hyalinizing angiectatic tumor of soft parts: a case report and literature review.Pathol Int. 2002 Oct; 52(10):664-8.

Pleomorphic hyalinizing angiectatic tumor of soft parts: immunohistochemical study including the expression of vascular endothelial growth factor.Arch Pathol Lab Med. 2000 Mar;124(3):423-6.

Pleomorphic hyalinizing angiectatic tumor of soft parts.Pathol Int. 1997 Nov;47(11):784-8.

Pleomorphic hyalinizing angiectatic tumor of soft parts: immunohistochemical case study shows cellular composition by CD34+ fibroblasts and factor XIIIa+ dendrophages.J Cutan Pathol. 1997 Jul;24(6):377-83.

Pleomorphic hyalinizing angiectatic tumor of soft parts. A low-grade neoplasm resembling neurilemoma.Am J Surg Pathol. 1996;20(1):21-9.