Primary Pseudomyogenic Hemangioendothelioma of Bone

Area of Science:

• Oncology
• Pathology
• Orthopedic Surgery

Background:

• Pseudomyogenic hemangioendothelioma (PMH) typically affects soft tissues, with bone involvement in 24% of cases.
• PMH solely in bone, without soft tissue extension, is exceptionally rare.
• This study presents the largest series to date of bone-exclusive PMH.

Purpose of the Study:

• To describe the clinicopathologic features of 10 rare cases of pseudomyogenic hemangioendothelioma exclusively involving bone.
• To enhance understanding of the presentation, imaging, histology, and immunohistochemistry of this rare bone neoplasm.
• To aid in the differential diagnosis of bone lesions with unusual morphology.

Main Methods:

• Retrospective analysis of 10 cases of bone-exclusive PMH.
• Review of clinical, imaging, histopathologic, and immunohistochemical findings.
• Genetic analysis for the t(7;19) translocation in relevant cases.

Main Results:

• The series included 9 males and 1 female, aged 12-74 years (mean 36.7).
• All patients presented with multiple tumors, frequently affecting the lower extremity (45%) or spine/pelvis (25%).
• Neoplasms showed well-circumscribed, lytic imaging features, composed of spindled and epithelioid cells with reactive woven bone and osteoclast-like giant cells; immunohistochemistry was positive for keratin, ERG, and CD31; t(7;19) translocation was noted in 3 cases.

Conclusions:

• PMH exclusively involving bone is rare, presenting as a multicentric disease often affecting the lower extremity.
• Unique morphological features, including reactive bone formation and giant cells, are characteristic.
• Accurate diagnosis requires distinguishing PMH from other vascular neoplasms, giant cell tumors, bone-forming tumors, and metastatic carcinoma due to its rarity and challenging presentation.