Epithelioid hemangiomas are benign vascular neoplasms made of epithelioid endothelial cell morphology usually seen in cutaneous and subcutaneous tissues.
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Epidemiology
They have been observed in all age groups with a peak incidence in the 4th decade. There is no gender predominance 1.
Diagnosis
The diagnosis of epithelioid hemangiomas is established by pathological features 1.
Diagnostic criteria
Diagnostic criteria according to the WHO classification of soft tissue and bone tumors (5th edition) 1:
- lobular structure with blood vessel formation
- endothelial cell lining of epithelioid cells with abundant eosinophilic cytoplasm and enlarged round nuclei
- loose edematous to hemorrhagic stroma with eosinophils in most cases
The following histological criterion is desirable:
- FOS/FOSB rearrangements
Clinical presentation
Frequently patients present with a single or (less commonly) multiple angiomatoid or erythematous cutaneous nodules which can be painless or slightly painful 1.
Pathology
Epithelioid hemangiomas are vascular tumors characterized by vessel formation, a lobular architecture, and a loose hemorrhagic stroma often interspersed with eosinophil infiltrates. The vessels feature an epithelioid endothelial cell lining 1.
Location
Epithelioid hemangiomas commonly involve the skin or subcutaneous soft tissues in the following locations 1,2:
- forehead
- preauricular region
- scalp
- extremities, in particular, distal extremities
- trunk
- rarely in large vessels
Macroscopic appearance
Macroscopically epithelioid hemangiomas have a nodular appearance and their size usually ranges from 0.5-2 cm at the time of presentation 1.
Microscopic appearance
Microscopic features of epitheloid hemangiomas include the following 1,2:
- lobulated growth
- multiple proliferative vascular channels
- a lining of large epithelioid, endothelial cells with eosinophilic cytoplasm and enlarged round nuclei with a "hobnailed" or "tombstone" pattern
- low mitotic activity
- inflammatory infiltrates within the stroma
Immunophenotype
Immunohistochemistry stains are usually positive for endothelial markers such as CD31, FLI1 and to a lesser extent ERG or CD34 as well as keratin or EMA 1,2.
Genetics
The pathogenesis of epithelioid hemangioma involves fusions of the FOS or FOSB gene in about half of cases 1.
Radiographic features
Radiologic imaging of epithelioid hemangiomas is rarely required due to their cutaneous or subcutaneous location and radiographic descriptions are therefore scarce 3.
Ultrasound
On ultrasound epithelioid hemangiomas might look like other hemangiomas with varying echogenicity and hypervascularity 3-5.
CT
CT might show soft tissue attenuation, iso- or hypointense to muscle with heterogeneous enhancement after contrast administration.
MRI
On MRI hemangiomas have a well-defined, solid, lobulated appearance with few intralesional flow voids 3-5.
- T1: isointense or hypointense to muscle
- T2: hyperintense to muscle with low signal intensity rings
- T1 C+ (Gd): moderate enhancement
Radiology report
The radiological report should include a description of the following:
- form, location and size
- tumor margins and transition zone
- distance from the muscular fascia
- regional lymph node involvement
Treatment and prognosis
Management usually includes resection and local recurrence occurs in up to one-third of the cases, but those can be treated or cured with re-excision. There are no known cases of distant metastases 1.
History and etymology
Epithelioid hemangiomas were first described as "angiolymphoid hyperplasia with eosinophilia" by George C Wells and Ian Wesley Whimster in 1969 6,7. Later those lesions were summarized together with bony lesions under the term "histiocytoid hemangioma" by the pathologist Juan Rosai in 1979 6-8. This term was subsequently abandoned due to potential diagnostic confusion 6,7.
Differential diagnosis
Conditions or tumors which can mimic the presentation and/or the appearance of epithelioid hemangiomas include 1-5: