A 52-year-old woman presented with a 5-month history of significant unintentional weight loss and anorexia, along with a more recent 2-week history of low-grade fever, progressive dyspnea, and dry cough. She denied hemoptysis, chest pain, wheezing, night sweats, or other systemic concerns. Her medical history was unremarkable, with no history of TB or atopic conditions. She was immunocompetent, with no known comorbidities or exposure to immunosuppressive agents or any long-term medications. She also denied any concerns suggestive of connective tissue disease. She was a wheat and sugarcane farmer, with no history of exposure to smoking, biomass fuel, occupational chemical exposure, recent travel, drug intake, or animal contact. She was a lifelong vegetarian, with no history of consumption of raw or undercooked meat or fish. She received a course of empirical antibiotics with no improvement in symptoms.

Trastuzumab-deruxtecan (T-DXd) is an antibody-drug conjugate associated with interstitial pneumonitis, affecting over 15% of patients receiving treatment. Initial management for grade 3/4 pneumonitis includes stopping the drug and administering high-dose steroids, but there is minimal guidance on additional treatment for steroid-refractory cases. We present a case of a 49-year-old woman with metastatic breast cancer who developed grade 4 pneumonitis after T-DXd treatment, who responded well to IV immunoglobulin (IVIG) after failing to respond to high-dose IV methylprednisolone. Most case reports and retrospective analyses to date have been done in pneumonitis associated with checkpoint inhibitors. To our knowledge, this is the first case report of a patient with steroid-refractory T-DXd pneumonitis positively responding to IVIG treatment. IVIG represents an attractive option as adjunctive therapy, given its minimal side effect profile compared with intensive immunosuppression. Further evidence is needed to help guide clinicians in managing drug-induced pneumonitis, including with T-DXd.

A 77-year-old woman had a 6-mm right upper lobe nodule that was under surveillance. It had originally been detected on a CT pulmonary angiogram to investigate breathlessness.

A 17-year-old male patient, suffering from pulmonary TB and undergoing treatment for the past 4 months, was referred to our institute for further evaluation of potential isoniazid-induced toxicity. The patient reported experiencing left arm pain for the past 2 months, which began gradually and worsened progressively. Initially, the pain was characterized by tingling and numbness, but it developed into severe burning sensations. The patient sought treatment at a local hospital, where the initial impression was that of isoniazid-induced neuropathy. He was managed with pain relief medications, multivitamins, and pyridoxine. Despite this treatment, the patient's pain did not subside and continued to worsen. His ability to grasp objects with his left hand was affected, significantly interfering with his daily activities.