Pneumonitis associated with bortezomib in a patient with multiple myeloma

Bortezomib, which is widely used in the treatment of multiple myeloma (MM), is a proteasome inhibitor and acts by inducing apoptosis. Bortezomib has many side effects, mainly hematological, neurological, and gastrointestinal. A few cases of bortezomib-induced pneumonitis (BIP) have been reported in the literature. A 51-year-old male patient who was newly diagnosed with MM received bortezomib, cyclophosphamide, and dexamethasone as first-line therapy. In the first cycle, the patient developed dyspnea, tachypnea, and hypoxia after the fourth day of administration of bortezomib monotherapy according to the treatment protocol. Infection and pulmonary involvement of MM were excluded after radiological evaluations, and a diagnosis of BIP was made. Clinical control was achieved quickly with steroid therapy and oxygen support, and radiological findings improved with treatment. Due to this rare side effect of bortezomib, the treatment regimen containing bortezomib was changed. The patient is still receiving treatment that does not contain bortezomib and does not have any pulmonary problems. In cancer patients receiving treatment, infection and metastasis should be quickly ruled out when pulmonary problems occur, and drug-induced pneumonitis should be considered. This diagnosis, which often responds dramatically to steroids, has the potential to have serious consequences when not considered. In this case, we present bortezomib-associated pneumonitis, a rare side effect of bortezomib. The most important feature of this case is the development of this side effect at the beginning of the treatment, unlike other cases reported in the literature.