[Multicenter skin tumor of the interdigitating dendritic cell]

Area of Science:

• Dermatopathology
• Immunohistochemistry
• Oncology

Background:

• Dendritic cells are crucial accessory cells in the immune system.
• Cutaneous dendritic cell tumors are rare and require precise classification.
• Understanding the origin and behavior of skin neoplasms is vital for diagnosis.

Observation:

• A 68-year-old male presented with a multicentric skin tumor characterized by papules and nodules.
• Lesions initially appeared on the arm and subsequently spread to extremities, shoulders, and face.
• Tumor cells exhibited positivity for Leu-6 (CD1), Leu-3a (CD4), HLA-DR/DQ, and S-100 protein.

Findings:

• Ultrastructural analysis revealed the absence of Birbeck granules, differentiating it from Langerhans cell histiocytosis.
• The tumor was identified as originating from interdigitating dendritic cells.
• A significant infiltrate of T-lymphocytes was noted within the cutaneous lesions.

Implications:

• This case expands the understanding of interdigitating dendritic cell tumors.
• The observed clinical course suggests a potentially indolent behavior with spontaneous regression phases.
• Further research into the immunobiology of these rare skin tumors is warranted.