Unusual histiocytic reaction to Monsel's solution

Area of Science:

• Dermatopathology
• Surgical Pathology
• Histology

Background:

• Monsel's solution (ferric subsulfate) is a topical hemostatic agent commonly used in dermatologic procedures.
• Basal cell carcinoma is the most common type of skin cancer, often treated with surgical excision.
• Accurate histopathological diagnosis is crucial for appropriate patient management.

Observation:

• A skin biopsy for basal cell carcinoma revealed an unusual intradermal nodule adjacent to the tumor.
• This nodule contained large polygonal cells and multinucleated giant cells laden with dark brown/black pigment.
• Perl's iron stain confirmed the pigment was hemosiderin, indicating iron deposition.

Findings:

• The observed histiocytic reaction and pigment deposition were directly associated with the topical application of Monsel's solution.
• The pigment was identified as iron, consistent with hemosiderin, a breakdown product of hemoglobin.
• This reactive process mimics certain neoplastic conditions, necessitating careful clinicopathological correlation.

Implications:

• Clinicians and pathologists must recognize this reactive histiocytic pattern to avoid misdiagnosis of melanoma or histiocytic neoplasms.
• Understanding this reaction aids in accurate interpretation of skin biopsies following Monsel's solution use.
• This highlights the importance of considering iatrogenic effects in histopathological assessments.