A 67-year-old post-menopausal lady was diagnosed to have metastatic hormone positive breast cancer in February 2019. Her imaging showed multiple bony metastases with few bilateral subpleural metastases (<1 cm). She underwent open reduction and internal fixation for a pathological fracture of her right neck of femur. Biopsy of the breast lump showed an infiltrating ductal carcinoma grade 1, Estrogen receptor (ER) + (Allred 8/8), progesterone receptor+ (PR+) and HER2 negative. She was a well-controlled hypertensive and had a background of bronchiectasis (Figure 1) for which she was asymptomatic. Her bronchiectasis was first diagnosed in 2 years prior to the current diagnosis of breast cancer, when she presented to another hospital was a probable infective exacerbation of underlying lung disease. She had no prior history of necrotising pneumonia in childhood or tuberculosis or features of ciliary dyskinesias/cystic fibrosis. There was no clinical or serological evidence of autoimmune disease (acute inflammatory markers were, however, elevated due to inflammatory, fumigating breast carcinoma). Acute infective aetiologies were also ruled out, with multiple blood and sputum cultures for bacteria, mycobacteria and fungi yielding no growth. Polymerase chain reaction (PCR) for viruses and mycobacteria was also negative. There was no evidence of immunocompromise other than underlying malignancy which was diagnosed subsequently in Feb 2019.
She was started on 3-monthly Zoledronic acid and palbociclib with Letrozole. There was significant reduction in size of the breast lesion, with healing of the breast ulcer and clinical improvement in terms of her bone pains. Four months later, she developed dry nonproductive cough and worsening breathlessness on exertion with no history of fever or prodromal illness. She was non-neutropenic with no renal or hepatic dysfunction. Arterial blood gas showed hypoxaemia and type 1 respiratory failure. Her high-resolution computed tomography (CT) thorax (Figure 2) was compared with her baseline imaging (Figure 1) and showed multiple new patchy and confluent ground glass opacities (GGOs) in bilateral lung fields, suggestive of acute interstitial lung disease (ILD).
A comprehensive workup including blood and sputum cultures was negative for bacterial, mycobacterial, fungal infections, influenza and pneumocystis carinii. Serological workup for underlying connective tissue disorder including anti-nuclear antibody, double-stranded DNA, Rheumatoid factor and anti-cyclic citrullinated peptide (CCP) was also negative. She was started on noninvasive ventilation and broad-spectrum intravenous (IV) antibiotics as she was unfit for a bronchoscopy/bronchoalveolar lavage (BAL) in view of her rapid deterioration. After a detailed discussion with the patient, she was started on IV methylprednisolone with an empirical diagnosis of drug induced pneumonitis. She refused aggressive treatment including ICU care, invasive ventilation and continued non-invasive ventilation. She was weaned off the noninvasive ventilation and was discharged on home oxygen therapy and letrozole. A follow-up CT was not performed as the patient clinically improved on systemic corticosteroids and antibiotics and she refused subsequent scans and opted for comfort care. Thus, after initiation of palbociclib in March 2019, palbociclib was discontinued in June 2019; after she developed the pneumonitis. She had also expressed her wishes against further imaging or invasive procedures. Therefore, bronchoscopy, trans-bronchial lung biopsy and/or BAL were not performed. She succumbed to her illness a month later at home.