Clear Cell Change in Reactive Angiogenesis: A Potential Diagnostic Pitfall.

Area of Science:

• Pathology
• Oncology
• Infectious Diseases

Background:

• Reactive angiogenesis is crucial for tissue repair, typically showing lobular capillary architecture with plump endothelial cells.
• A poorly described variant of reactive angiogenesis features large endothelial cells with clear cytoplasm, creating diagnostic difficulties.

Purpose of the Study:

• To describe a distinct form of reactive angiogenesis characterized by clear cell change in endothelial cells.
• To differentiate this entity from other conditions, including tumors and infections, based on histological and immunohistochemical findings.

Main Methods:

• Histopathological examination of 10 patient cases (bone and soft tissue).
• Immunohistochemical staining for endothelial markers (CD31, ERG, CD34, FLI1) and exclusion markers (keratin, CD68).
• Periodic acid-Schiff (PAS) and PAS-diastase staining, and polymerase chain reaction (PCR) for Bartonella henselae.

Main Results:

• The study identified 10 cases with lobular capillary proliferation lined by large, clear/pale eosinophilic endothelial cells.
• Immunohistochemistry confirmed endothelial origin (positive for CD31, ERG, CD34, FLI1) and negativity for keratin and CD68.
• PAS staining excluded glycogen, and PCR was negative for Bartonella henselae.

Conclusions:

• A unique reactive angiogenesis with clear cell change, unassociated with Bartonella, is described.
• This entity presents diagnostic challenges, necessitating differentiation from benign/malignant neoplasms and infections.
• Accurate diagnosis is critical due to significant implications for patient treatment and prognosis.