B35-16 Beyond the Skin: Pulmonary Manifestations of Pyoderma Gangrenosum

Abstract Background Pyoderma gangrenosum (PG) is an uncommon neutrophilic dermatosis that may involve extracutaneous organs such as the lungs. Pulmonary PG can present with nodular, cavitary, or infiltrative lesions. Necessary exclusion of infectious, malignant, vasculitic, granulomatous, or other autoimmune etiologies can lead to diagnostic delay. Case report A 55-year-old woman with biopsy-proven cutaneous PG presented with progressive cough and dyspnea. Chest imaging (image 1) showed enlarging cavitary lesions despite corticosteroid treatment and broad antimicrobial therapy. Serial microbiologic testing, including bacterial, mycobacterial, and fungal cultures, remained negative. Galactomannan and beta-D-glucan assays were unremarkable. CT-guided lung biopsy revealed chronic lymphocytic inflammation with scattered eosinophils and neutrophils without granulomas or malignancy. Bronchoscopy with bronchoalveolar lavage was nondiagnostic and bacterial-, fungal- cultures were negative. The patient was considered for adalimumab for refractory cutaneous PG but deferred due to concern for monoclonal gammopathy of undetermined significance (MGUS). She subsequently received intravenous immunoglobulin but was discontinued due to infusion reaction. Given the sterile inflammatory histology, negative microbiologic evaluation, and known cutaneous PG, pulmonary PG was considered the most likely diagnosis. Multidisciplinary discussion with hematology and dermatology led to a plan for bone marrow biopsy, with bortezomib considered for MGUS-related disease modulation versus adalimumab if the biopsy is benign. Discussion Pulmonary PG is exceedingly rare, with fewer than thirty published cases. Lesions may occur before, during, or after cutaneous involvement. Histopathology is nonspecific but typically demonstrates a sterile dense neutrophilic infiltrate with later lesions demonstrating a mixed inflammatory infiltrate. A rapid response to corticosteroids helps distinguish PG from infectious conditions. Treatment centers on immunosuppression with high-dose corticosteroids (0.5-1 mg/kg/day) or cyclosporine (3-5 mg/kg/day), often with rapid response. In refractory or corticosteroid-intolerant cases, biologic agents such as infliximab and adalimumab have shown benefit, particularly in patients with inflammatory comorbidities. Adjunctive therapies such as plasma-cell-directed regimens may be considered in MGUS-associated or refractory disease. Bortezomib, a proteasome inhibitor primarily used in multiple myeloma, has been reported in rare, exceptional cases to induce remission of refractory, disseminated PG when associated with underlying monoclonal gammopathy or smoldering myeloma. In such cases, bortezomib was used to target hematologic disorder, resulting in resolution of PG lesions. Conclusion Pulmonary PG should be considered in patients with known PG disease who present with cavitary lung lesions unresponsive to antibiotics and lacking infectious or malignant etiology. Early recognition and initiation of immunosuppressive therapy can be both diagnostic and therapeutic. This abstract is funded by: None