Sarcoidosis Mimicking Metastatic Disease: A Case Report

A 64-year-old female with no significant past medical history (except appendectomy, tubal ligation, mammoplasty, and hysteropexy) presented with a persistent non-productive cough that had lasted for over a month. A chest X-ray revealed prominent hilar structures and ground-glass opacities in the lower lung zones, which is suggestive of either a granulomatous or an infiltrative process (Figure 1). She was subsequently referred to a pulmonologist who, after clinical evaluation, reassured her and provided symptomatic management with instructions to monitor for signs of respiratory infection. As the symptoms persisted, a high-resolution chest CT scan was performed. It demonstrated bronchial wall thickening, ground-glass opacities in the lower lungs, pleural thickening at the bases, numerous nodular lesions throughout the lungs, and enlarged lymph nodes in the mediastinal, hilar, and pericardial regions. These imaging findings raised the differential diagnoses of granulomatous disease, infiltrative processes, lymphoma, and metastasis. Nevertheless, no specific therapeutic intervention was initiated at that time. Further cardiac evaluation, including an echocardiogram, revealed a normal left ventricular ejection fraction of 63% and a pulmonary artery pressure of 16 mmHg, both within normal limits. The patient was again reassured and advised to continue symptomatic management, including routine precautions for respiratory infections.

Over the ensuing eight months, the patient continued to experience a non-productive cough accompanied by significant weight loss of approximately 20 kilograms. Despite the persistence of symptoms, she did not seek additional medical care until an acute respiratory infection aggravated her condition, with worsening cough and new-onset lumbar pain that was exacerbated by coughing. This prompted further medical evaluation. Two months later, an MRI of the lumbar spine was performed, which revealed degenerative changes, decreased disc height, grade 1 spondylolisthesis at L4–L5 and L5–S1 levels, and sclerotic lesions in the L1 vertebral body and posterior superior aspect of L5 (Figure 2). A pelvic MRI showed abnormal signal intensities along the lateral border of the sacrum and adjacent iliac bones. A contrast-enhanced MRI further revealed enhancing lesions involving the right sacral wing, upper border of the right iliac bone, and the lower border of the left iliac bone. These findings raised a strong concern for metastatic lesions. A follow-up contrast-enhanced lumbar MRI revealed enhancement in the L1 vertebral body and the posterior superior aspect of L5, strongly suggestive of blastic metastatic disease.

Based on these findings, a whole-body bone scan was recommended to assess the full extent of skeletal involvement. Additionally, a PET scan demonstrated hypermetabolic activity in the L1 and L3 vertebrae, right femur, bilateral iliac bones, and sacrum, further reinforcing the initial impression of metastatic disease. To investigate the possibility of an underlying malignancy, the patient underwent excisional biopsies of the cervical and right axillary lymph nodes. Histopathological analysis revealed chronic granulomatous lymphadenitis, characterized by non-necrotizing granulomas composed of aggregates of epithelioid histiocytes and multinucleated giant cells. PCR testing for tuberculosis was negative. Although these findings were consistent with sarcoidosis, the possibility of “sarcoid-like” granulomas secondary to malignancies such as Hodgkin lymphoma, lymphoproliferative disorders, or germ cell tumors could not be excluded at this stage [7].

Given the extensive distribution of hypermetabolic lesions, including hepatic and splenic enhancement on PET scan (Figure 3), liver biopsy was subsequently performed to rule out disseminated malignancy. Histological examination of the liver tissue revealed non-caseating granulomatous inflammation without evidence of malignancy, thereby confirming the diagnosis of sarcoidosis. Following confirmation of the diagnosis, the patient was referred to rheumatology. She started low-dose corticosteroid therapy with 10 mg of prednisolone daily, which led to significant improvement in bone pain. With malignancy definitively ruled out, she was subsequently considered a candidate for methotrexate as a steroid-sparing agent. Additionally, given evidence of low bone mineral density and absence of hypercalcemia or hypercalciuria, osteoporosis was diagnosed and managed with intravenous bisphosphonate therapy under close metabolic monitoring.