A case of cutaneous collagenous vasculopathy associated with multiple myeloma and with a pathogenic variant of the glucocerebrosidase gene.

Cutaneous collagenous vasculopathy (CCV) is an extremely rare acquired microangiopathy of unknown etiology. The authors describe a case of a 68-year-old man, a carrier of a heterozygous pathogenic variant of the glucocerebrosidase (GBA) gene, who was diagnosed with CCV, revealing uncommon fibrinogen positivity in direct immunofluorescence. The patient was subsequently diagnosed with multiple myeloma. Treatment of the myeloma with combined chemotherapy including bortezomib, followed by autologous stem cell transplantation, led to significant reduction of cutaneous lesions. To the best of the authors' knowledge, this is the first published case of CCV in a carrier of a pathogenic variant of the GBA gene, associated with multiple myeloma and with significant regression of CCV after myeloma treatment. Direct immunofluorescence examination revealed an unusual fibrinogen deposition. Hypothetical causative role of bortezomib treatment was proposed regarding significant regression of CCV.