Sarcoid-like reaction: a unique response to immunotherapy in malignant melanoma.

In recent years, immunotherapy has revolutionised the treatment landscape for oncology patients with improved survival rates in cancers which previously had a dismissal prognosis. These agents target specific pathways of inhibition such as programmed cell death -1 (PD-1), PD ligand-1 and cytotoxic T-lymphocyte-associated antigen 4 resulting in stimulation of T cell activity. This results in enabling an individual's own immune system to fight against cancer, a different modality of treatment when compared with traditional chemotherapy. While attacking the tumour cells, there is an increased chance of host tissue immune reactions.We report a case of a patient who received immunotherapy for metastatic malignant melanoma. During the course of the treatment, development of a sarcoid-like reaction was histologically confirmed in the mediastinal lymph nodes. The patient had no respiratory symptoms and continued on the immunotherapy treatment with good clinical and radiological response.