Angiomyofibroblastoma

Definition

This is a benign myofibroblastic tumour of superficial soft tissues with a predilection for the vulval region.

Epidemiology

This is an uncommon tumour, of similar incidence to aggressive angiomyxoma. It most often occurs in women of childbearing age.

Clinical features

Most cases occur in the vulva, less often in the vagina5. Rare cases occur in males, in the scrotum or paratesticular tissues6.

Macroscopic appearance

The tumour is well demarcated but not encapsulated. It has a tan pink cut surface.

Histopathology

There is a thin pseudocapsule. Cellularity is variable. There is typically a perivascular accentuation of tumour cells. Tumour cells vary from round to spindle and have eosinophilic cytoplasm. There are frequent binucleate and multinucleate cells. Sometimes the cells are plasmacytoid with eccentric nuclei, or epithelioid. There may be hyperchromatic degenerative nuclear changes. There are abundant arborising blood vessels throughout, from capillaries to medium-size vessels. An adipocytic component is seen in 10% of cases (lipomatous variant of AMF)4,5. The stroma is loose and oedematous. In postmenopausal women, the stroma is more fibrous with hyalinisation. Mitoses and necrosis are lacking.

Immunohistochemistry

vimentin	positive
desmin	positive, strongly and diffusely, reduced in the postmenopausal
SMA	positive focally
oestrogen receptor	positive
progesterone receptor	some cases positive
CD34	some cases positive4
factor XIIIa	negative
cytokeratins	negative
S-100	negative
muscle-specific actin	negative or weakly positive3
fast myosin	negative
CD57 (Leu7)	negative
GFAP	negative
CD68	negative

Ultrastructure

There is well-developed rough endoplasmic reticulum, Golgi apparatus, abundant intermediate filaments, and pinocytotic vesicles in the stromal cells1.

Differential diagnosis

Clinically most often diagnosed as a Bartholin's gland cyst.
Aggressive angiomyxoma: usually larger, deeper and infiltrative; cellularity is lower and blood vessels are less numerous. There is erythrocyte extravasation.

Prognosis

Simple resection is curative. There is a single case report of sarcomatous transformation (angiomyofibrosarcoma)2.

References

Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, page 75

World Health Organization Classification of Tumours, Tumours of Soft Tissues and Bone, IARC Press 2002.

1Fletcher, C. D., W. Y. Tsang, et al. (1992). "Angiomyofibroblastoma of the vulva. A benign neoplasm distinct from aggressive angiomyxoma." Am J Surg Pathol 16(4): 373-82.

2Nielsen, G. P., R. H. Young, et al. (1997). "Angiomyofibroblastoma of the vulva with sarcomatous transformation ("angiomyofibrosarcoma")." Am J Surg Pathol 21(9): 1104-8.

3Fukunaga, M., K. Nomura, et al. (1997). "Vulval angiomyofibroblastoma. Clinicopathologic analysis of six cases." Am J Clin Pathol 107(1): 45-51.

4Laskin, W. B., J. F. Fetsch, et al. (1997). "Angiomyofibroblastoma of the female genital tract: analysis of 17 cases including a lipomatous variant." Hum Pathol 28(9): 1046-55.

5Nielsen, G. P., A. E. Rosenberg, et al. (1996). "Angiomyofibroblastoma of the vulva and vagina." Mod Pathol 9(3): 284-91.

6Ockner, D. M., H. Sayadi, et al. (1997). "Genital angiomyofibroblastoma. Comparison with aggressive angiomyxoma and other myxoid neoplasms of skin and soft tissue." Am J Clin Pathol 107(1): 36-44.

This page last revised 30.6.2004.