[Two cases of granuloma annulare under anti-PD1 therapy].

BACKGROUND

Granuloma annulare as a granulomatous cutaneous reaction may be drug-induced. Immune checkpoint inhibitors including programmed death-1 (PD-1) inhibitors show remarkable antitumor activity and are approved for melanoma and other cancers. Different immune-related adverse effects have been described. We report herein a rare adverse effect of anti-PD1 therapy given for metastatic melanoma : granuloma annulare.

PATIENTS AND METHODS

Two women receiving pembrolizumab metastatic melanoma presented with granuloma annulare. The therapy was continued in both cases. In the first patient, granuloma annulare appeared and then subsided; in the second patient, the lesion resolved completely with topical corticosteroids.

DISCUSSION

While there have been reported cases of sarcoidosis induced by immunotherapies, immunotherapy-induced granuloma annulare has not been described. The pathogenesis of drug-induced granulomatous reactions is thought to involve autoimmune dysregulation affecting T cells, especially Th1 cells, which lead to granuloma formation. Granuloma annulare should thus be considered a cutaneous adverse effect of anti-PD1 immunotherapy.