Vemurafenib-induced histiocytoid neutrophilic panniculitis simulating myeloid leukaemia cutis

Area of Science:

• Dermatology
• Oncology
• Pharmacology

Background:

• BRAF inhibitors (BRAFi) are associated with neutrophilic panniculitis, a rare adverse event.
• Vemurafenib, approved in 2011, has had limited reports of neutrophilic panniculitis outside of melanoma.
• Histiocytoid infiltrates of immature neutrophils can mimic other conditions like myeloid leukemia cutis.

Observation:

• A novel variant of neutrophilic panniculitis was identified in an early lesion.
• The patient had metastatic colon carcinoma and was treated with vemurafenib combined with an anti-EGFR agent.
• The histiocytoid myeloid cell infiltrate was noted three weeks after therapy initiation.

Findings:

• Described a unique presentation of neutrophilic panniculitis characterized by histiocytoid myeloid cells.
• This variant occurred in a non-melanoma malignancy (colon carcinoma) under combination therapy.
• The infiltrate was observed in an early-stage lesion.

Implications:

• Early recognition of this BRAFi-associated panniculitis variant is crucial.
• Distinguishing this condition from myeloid leukemia cutis is important for accurate diagnosis and patient management.
• Highlights the need for vigilance regarding dermatologic adverse events in targeted cancer therapy.