Angiomyofibroblastomas are benign mesenchymal neoplasms usually found in the pelvis or perineum, especially the vulva.
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Epidemiology
Angiomyofibroblastomas are uncommon tumors predominantly found in adult women usually between menarche and menopause. Approximately 10% of these tumors have been described in postmenopausal women. In men, they are rare 1.
Diagnosis
The diagnosis of angiomyofibroblastoma is established histologically 1.
Diagnostic criteria
Diagnostic criteria according to the WHO classification of tumors: soft tissue and bone (5th edition) 1:
- prominent well-defined stromal vessels
- round to spindle-shaped frequently multinucleated perivascular tumor cells
The following criterion is desirable:
- desmin positivity on immunohistochemistry
Clinical presentation
The usual complaint is a slowly progressive well-defined painless mass 1.
Pathology
Angiomyofibroblastomas are well-circumscribed myofibroblastic lesions characterized by prominent stromal vessels surrounded by round to ovoid or spindle-shaped tumor cells 1-4.
Etiology
The etiology of angiomyofibroblastoma is unknown 1.
Location
Most angiomyofibroblastomas are found in the perineal region with most being located in the vulva or perineum followed by the vagina and uterine cervix. They can occur in other regions for example in the mediastinum or nasal cavity but only on very rare occasions 1-4.
Macroscopic appearance
Macroscopically angiomyofibroblastomas are well-demarcated lesions, they are not encapsulated and some might be pedunculated. They usually have a soft consistency and are of pink-tan color 1.
Microscopic appearance
The histological appearance of angiomyofibroblastomas is characterized by the following features 1-4:
- thin fibrous pseudocapsule
- prominent thin-walled ectatic vessels in an edematous matrix
- round to ovoid epithelioid or spindle-shaped tumor cells with eosinophilic cytoplasm
- well-differentiated adipocytic components in about 10% of cases
- degenerative nuclear atypia
- rarely morphological overlap with aggressive angiomyxoma
Immunohistochemistry
Immunohistochemistry stains express vimentin and are usually positive for desmin, unless in postmenopausal women. There is only a focal expression of smooth muscle actin (SMA) and muscle-specific actin (MSA). In addition tumor cells usually express estrogen receptors, progesterone receptors and occasionally CD34 1.
Radiographic features
Angiomyofibroblastomas are usually solid well-demarcated vascularized lesions.
Ultrasound
There is some variability concerning ultrasound findings. On one hand, angiomyofibroblastomas have been described as solid-cystic-appearing lesions with inhomogeneous echogenicity on the other hand homogeneous appearing lesions have also been described. Color Doppler imaging usually displays intralesional or peripheral vascularization 2-4.
MRI
Angiomyofibroblastomas appear as solid well-circumscribed variably heterogeneous soft tissue masses 2-4.
Signal characteristics
- T1: low to intermediate signal intensity
- T2: heterogeneous mixed to high signal intensity
- T1 C+ (Gd): intense enhancement with variable heterogenicity
Radiology report
The radiological report should include a description of the following:
- location and size of the tumor
- relation to other organs
- relation to soft tissue structures structures
Treatment and prognosis
The main treatment is surgical excision. Angiomyofibroblastomas are benign and have an excellent prognosis with local recurrences being reportedly rare even with marginal excision 1,2,6.
History and etymology
Angiomyofibroblastoma was initially described by the British pathologist Christopher DM Fletcher and colleagues in 1992 2-5,8.
Differential diagnosis
Conditions with similar clinical presentation or appearance of angiomyofibroblastomas include 1-4:
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