Abstract

A 49-year-old female with history of poorly differentiated gallbladder adenocarcinoma and invasive ductal carcinoma of the breast on pembrolizumab 400mg every 6 weeks presented with nodules on the hands. They had been present for about three months prior to presentation and were relatively asymptomatic. At the time of initial symptom onset, she had been traveling in Mexico, and had reported that she picked flowers and petted a stray cat while there. She was seen by her oncologist, who thought this may represent sporotrichosis. She was placed on itraconazole 200mg daily but continued to develop new nodules and was subsequently referred to Dermatology. Exam demonstrated multiple subcutaneous skin colored to pink papules at the lateral and dorsal aspects of the second and fifth digits bilaterally. Punch biopsies were obtained for H&E and culture. Pathology demonstrated prominent palisading granulomas composed of epithelioid histiocytes and multinucleated giant cells. Colloidal iron stain demonstrated a mild focal increase in interstitial dermal mucin. Bacterial, fungal, and mycobacterial tissue cultures were negative. She was ultimately diagnosed with pembrolizumab-associated granuloma annulare. Prior to her vacation, her pembrolizumab dosing was changed from 200mg every 3 weeks to 400mg every 6 weeks, which may have triggered the development of granuloma annulare. Granulomatous reactions including sarcoidosis-like reactions, granulomatous panniculitis, granulomatous dermatitis, and granuloma annulare to immune checkpoint inhibitors (ICIs) have been described in the literature and typically occur after 2 months to 8 months of therapy. In our case, the patient’s granuloma annulare resolved after returning to the decreased and more frequent dosing. Clinicians should consider granuloma annulare in patients treated with ICIs and should discuss dose adjustments with the treating oncologists to mitigate the disease.

Financial Disclosure:
No current or relevant financial relationships exist.