Abstract Introduction Dendriform pulmonary ossification (DPO), the formation of mature bone tissue in the lungs, is a rare cause of parenchymal lung disease. It is often found incidentally via imaging or autopsy, can be idiopathic or secondary to inflammatory and infectious conditions, and is more common in elderly males. Here, we present a case of idiopathic DPO in a young adult female. Case Report A 37-year-old female with a history of obstructive sleep apnea (OSA) and obesity presented for evaluation of 4 years of chronic hypoxemia following hospitalization for SARS-CoV-2 infection in 2020. Following her infection she required 2L oxygen at all times. Cardiopulmonary exam was unremarkable, however, sclerodactyly and hyperkeratosis of the hands and feet were noted. Echocardiogram and cardiac stress test returned negative. Spirometry was negative for obstructive or restrictive physiology. High-resolution CT (HRCT) scan demonstrated pulmonary calcifications that on retrospective review were present in 2020 but had since progressed (Figure 1A-B). Her imaging findings were presented at lung conference and biopsy was recommended to establish a diagnosis. She underwent video assisted thoracoscopic surgery with surgical lung biopsy that under histopathologic review revealed cicatricial ossifying pneumonia (CiOP) and patchy follicular bronchitis consistent with DPO (Figure 1C-D). A cursory autoimmune workup was negative and repeat HRCT 6 months later was stable. Due to uncertain etiology and progression, she was referred to a lung transplant center for early evaluation. Discussion DPO often occurs secondary to an inflammatory insult that causes pulmonary fibroblasts to transform into osteoblasts and generate intrapulmonary osseous tissue. Common predisposing conditions include fibrotic interstitial lung disease, SARS-CoV-2 infection, pneumoconioses, and chronic aspiration. Our patient’s primary risk factor prior to her SARS-CoV-2 infection was OSA, however, her severe COVID-19 infection may have contributed to the progression of her disease. While often identified incidentally, it can be progressive and lead to or worsen ventilatory impairment. No targeted therapies exist, and treatment often aims at addressing the underlying etiology. In advanced or progressive cases, patients may require a lung transplant. Figure 1: A-B) Inspiratory, supine images from HRCT demonstrating diffuse high-density linear nodular opacities, C) Histopathological images demonstrating ossified lesions (arrows) and fat-containing marrow components (star). D) High-magnification histopathology demonstrating disruption of normal alveolar architecture due to CiOP. Scale bar: 300 μm. This abstract is funded by: None
Morrison et al. (Fri,) studied this question.