C40-32 Atypical Systemic Sarcoidosis Mimicking Widespread Malignancy

Introduction Sarcoidosis is a multi-system inflammatory disorder defined by non-caseating granulomas. While the disease most commonly affects the lungs and intrathoracic lymph nodes, it is known for its highly variable presentations. Atypical sarcoidosis, particularly that involving extensive extrapulmonary sites, often poses a significant diagnostic challenge, frequently mimicking widespread metastatic malignancy. We report a case of systemic sarcoidosis with aggressive pulmonary, abdominal, and skeletal involvement that required extensive workup for definitive diagnosis. Description of Case A 69 year old female with a known history of coronary artery disease, SVT, and osteoporosis, was incidentally found to have innumerable bilateral pulmonary nodules and widespread extrapulmonary involvement during a routine CT scan for aortic aneurysm surveillance by her cardiologist. Due to the aggressive imaging findings, the patient was referred to oncology for evaluation. A subsequent PET scan revealed extremely aggressive, hypermetabolic disease. This included extensive hypermetabolic lesions in the mediastinal, hilar, mesenteric, peripancreatic, retroperitoneal, and iliac chain regions, in addition to countless hypermetabolic splenic lesions and low-grade metabolically active lesions in the cervical spine, left sacroiliac pelvis, and posterior left acetabulum. The patient initiated treatment with a prednisone taper and the steroid-sparing agent CellCept. Follow-up imaging demonstrated a dramatic and complete therapeutic response: a repeat PET scan confirmed interval metabolic resolution of the pulmonary nodules, splenic lesions, and the extensive lymphadenopathy across all previously active sites (mediastinal, hilar, abdominal, and skeletal). This significant metabolic and morphologic regression provided definitive confirmation of the sarcoidosis diagnosis. Concurring with a second opinion from a higher center, the patient was successfully tapered off steroids and discontinued CellCept due to complete remission. Pulmonary function testing on resolution showed normal spirometry but a residual mild reduction in diffusion capacity. Discussion This case presentation encompassed atypical manifestations of Pulmonary sarcoidosis featuring diffuse, innumerable nodules and hypermetabolism. This deviation from typical findings raised suspicion for malignancy. The extrapulmonary disease was remarkably aggressive, particularly the massive systemic lymphadenopathy and hypermetabolic splenic lesions (reported in < 10% of cases), a common differential for lymphoma or metastasis. Diagnosis was definitively confirmed by transbronchial and splenic biopsies, revealing classic non-caseating granulomatous inflammation with negative cultures (BAL). Importantly, PET ruled out acute myocardial inflammation, a critical and potentially fatal complication. This case underscores the crucial need for an aggressive approach and early tissue diagnosis when sarcoidosis presents atypically, and highlights the potential for successful treatment even of aggressive phenotypes.