Linear and Bilateral Multinucleated Cell Angiohistiocytoma (MCAH)

Area of Science:

• Dermatology
• Pathology
• Vascular Lesions

Background:

• Multinucleated Cell Angiohistiocytoma (MCAH) is a rare vascular neoplasm, with fewer than 100 cases documented since its 1985 description.
• Typically presents as papules or plaques on extremities, hands, or face, though generalized forms exist.

Observation:

• A 77-year-old woman presented with multiple, itchy, reddish-to-violaceous plaques on her lower legs.
• Lesions exhibited a symmetrical, bilateral distribution along the saphenous veins.
• Dermoscopy revealed a homogeneous red-violaceous area; histology showed vascular proliferation and multinucleated giant cells.

Findings:

• Histopathology confirmed MCAH, characterized by dilated small vessels and atypical multinucleate giant cells with scalloped cytoplasm.
• Numerous mast cells were observed adjacent to multinucleate cells.
• This case is the first documented MCAH with a bilateral, linear pattern along the saphenous veins.

Implications:

• The linear distribution along saphenous veins suggests a potential role for chronic trauma, such as from ambulation, in lesion development.
• Highlights the importance of detailed clinico-pathologic correlation for diagnosing rare vascular tumors.
• Contributes to the understanding of MCAH's varied clinical presentations and potential pathomechanisms.