epithelioid hemangioma of the bone
Digital cases
Case 162 (HPC:162) : Epithelioid hemangioma of bones (Hand)
Definition: Epithelioid hemangioma of bone is a benign lesion that may be multifocal and affect separate tissue and is successfully treated with curettage or marginal en bloc excision.
Nosology
Many tumors classified as "low-grade hemangioendothelial sarcoma" actually represented examples of EH.
The use of the unqualified term “hemangioendothelioma” in relation to vascular tumors of bone has diminished, and the WHO has recognized EH as a distinct entity of bone, and lists the term "hemangioendothelioma" as a synonym for "angiosarcoma".
Regardless, these tumors are still often confused with malignant endothelial neoplasms, especially "epithelioid hemangioendothelioma".
Radiology
On conventional x-rays and computed tomography scans, the lesions are usually lucent, with well-defined margins but are less so on magnetic resonance images.
Macroscopy
In a few cases, especially those involving small tubular bones, the bone is expanded and focally destroyed with tumor extending into adjacent soft tissue. The size of the tumors is known in 14 patients and they ranged from 1 to 7 cm in diameter.
Grossly, they were soft, solid, red, and hemorrhagic. Tumors excised intact with the involved bone were relatively well circumscribed and frequently expanded the bone.
Uncommonly, tumors erode the cortex and extend into the soft tissues with pushing margins.
The tumors can be dome shaped and red and violaceous.
Microscopy
slight male predominance
age from 10 to 75 (mean 35) years
localization
- long tubular bones (40%)
- short tubular bones of the distal lower extremity (18%)
- flat bones (18%)
- vertebrae (16%)
- small bones of the hands (8%).
18% of patients have involvement of more than 1 bone.
Prominent reactive woven bone sub can compartmentalize the tumor into small nodules.
The neoplasm has a lobular architecture, replaced the marrow spaces, and often infiltrated between and surrounded preexisting bony trabeculae. The periphery of the lobules sometimes contained many small arteriolar-like vessels lined by flat endothelial cells.
The central areas of the lobules were cellular and composed of epithelioid endothelial cells that formed vascular lumina or grew in solid sheets.
The epithelioid endothelial cells are large and polyhedral. Their nuclei are oval or kidney bean shaped, tend to be hyperlobated or cleaved, and contained finely distributed chromatin.
The cytoplasm is abundant, deeply eosinophilic, and occasionally contained one or a few vacuoles that were round, clear, and sometimes contained an intact or fragmented red blood cell.
In some instances, cells with vacuoles aggregated with one another such that neighboring vacuoles seemed to coalesce to form vascular lumens.
Most tumors contain many well-formed vessels lined by the epithelioid cells that sometimes protruded into the lumens in a tombstone-like fashion. In some tumors, solid cellular sheet-like areas predominate, whereas, in others it accounts for just small portions of the neoplasm.
Mitoses, even in the cellular areas, are relatively infrequent and always of normal structure. Small foci of necrosis were present in a minority of otherwise typical cases. The stroma consisted of loose connective tissue, and in some cases contained a prominent inflammatory infiltrate rich in eosinophils. No hyalinized or myxoid extracellular matrix was present.
Foci of intralesional hemorrhage were present in some tumors, especially those involving the short tubular bones of the extremities. These areas also contained proliferating, cytologically banal, spindle cells that were often arranged in fascicles.
Other infrequent findings include scattered intratumoral osteoclast-type giant cells, reactive bone formation which compartmentalized the tumor into small nodules, and the presence of a large dilated vessel lined by epithelioid endothelial cells located within the center of the tumor.
Radiology
Radiographically, the lesions are lucent and well marginated.
Microscopy
Microscopically, the neoplasms had a lobular architecture and were composed of epithelioid endothelial cells that formed obvious vascular lumina or grew in solid sheets. No hyalinized or solid appearing extracellular myxoid matrix was present.
Multiple tumors
Some patients have been described with separate lesions involving both bone and soft tissue or parenchymal organs. Some patients have discontinuous lesions of bone, skin, artery, and lymph node and one patient described had a lesion in bone and a separate nodule of tumor in the lung.
EH of bone, similar to conventional hemangioma of bone, may present with multiple non-contiguous intraosseous tumors. This is especially true when EH arises in the digits.
The individual lesions, like the multiple separate enchondromas in enchondromatosis, are viewed as an expression of multicentricity and not metastatic disease.
So, is the situation different when this type of vascular tumor involves bone and skin simultaneously, or bone and another other organ system, which has been reported to be a primary site for EH.
The natural history of the disease is essential in addressing this issue. In view of the fact that all published cases of EH, regardless of site of origin and extent of distribution within the body, have behaved in a banal fashion in that they have not demonstrated disseminated growth that can be construed as aggressively destructive or life threatening, supports the concept that EH of bone is benign, like its cutaneous counterpart, and that involvement of multiple organ systems simultaneously, is more likely a manifestation of multicentricity rather than metastatic disease.
A case of epithelioid hemangioendothelioma of the rib and adjacent intercostal lymph nodes and a patient with EH of the second toe and subsequent involvement of the inguinal, iliac, and para-aortic lymph nodes have been reported.
Differential diagnosis
epithelioid vascular tumors
- epithelioid hemangioendothelioma
- epithelioid angiosarcoma
Other vascular tumors that can demonstrate epithelioid features and should be considered in the differential diagnosis of EH of bone include:
hemorrhagic epithelioid and spindle cell hemangioma
- "hemorrhagic epithelioid and spindle cell hemangioma" is now believed that they are a variant of EH.
epithelioid hemangioendothelioma
- Epithelioid hemangioendothelioma can be distinguished from EH because the epithelioid cells are arranged in cords, show greater degree of atypia and importantly, unlike EH, are enmeshed in a hyalinized or chondroid matrix.
epithelioid angiosarcoma.
- Epithelioid angiosarcoma, in contrast to EH exhibits overt cytologic features of malignancy with significant cytologic atypia and increased mitotic activity, including atypical forms.
Management
EH of bone should be treated with curettage or marginal en bloc excision when appropriate, and has an excellent prognosis. Most of the patients in the series are treated with curettage.
Some receive radiation treatment. Radiation was given to help prevent another recurrence.
In contrast, epithelioid hemangioendothelioma should be widely excised and although the prognosis is good, a significant number of cases metastasize and prove to be fatal.
Epithelioid angiosarcoma needs to be widely excised and consideration should be given to systemic therapy, as these tumors are very aggressive and most patients die of metastatic disease.
These differences in treatment and prognosis emphasize the importance of accurately distinguishing between these benign and malignant neoplasms.
Immunohistochemistry
CD31 +
factor VIIIrAg +
CD34 +
+/- keratins
+/- focal muscle-specific actin-positive myopericytic cells
See also
Vascular tumors of bones
- epithelioid vascular tumors of bones
References
Epithelioid hemangioma of bone revisited: a study of 50 cases. Nielsen GP, Srivastava A, Kattapuram S, Deshpande V, O’Connell JX, Mangham CD, Rosenberg AE. Am J Surg Pathol. 2009 Feb;33(2):270-7. PMID: #18852673#