40-year-old woman with melanoma of the right knee

A teaching case from MD Anderson Cancer Center

Behrang Amini

40-year-old woman with right knee melanoma

Wide local excision 6 years ago with negative sentinel lymph node biopsy

Liver and mesenteric mets 1 year ago

Started therapy with dabrafenib and trametinib 2 months ago

Most recent PET was negative

Presents with FDG PET/CT below: 
 

Note multiple sites of new uptake in the lower limbs, more numerous on the left (primary was in the right knee)

Axial fused PET/CT shows subcutaneous location of lesions

Axial CT image shows uptake localizing to subtle increased attenuation

Initial instinct is to call this metastatic disease and change therapy.

This is BRAF inhibitor-induced paniculitis.

Currently three BRAF inhibitors are approved in Europe and US for the treatment of patients with BRAF-mutant advanced melanoma: 

Vemurafenib

Dabrafenib

Encorafenib