Abstract
A 69-year-old female with recurrent stage IV squamous cell lung carcinoma and metastatic abdominal lymph node but not bone metastases was being treated with pembrolizumab. Four months after starting the recurrent treatment, the tumour reduced in size but she began to complain of back pain and palmar rash. A bone scan showed uptake lesions in the left sternocostal joints and vertebrae, while spine magnetic resonance imaging (MRI) showed multiple lesions in the thoracic vertebrae. Her heterogeneous lesions, such as skin and multiple bone manifestations, were comprehensively diagnosed as SAPHO syndrome by different experts. Furthermore, the SAPHO syndrome was suspected to be an immune-related adverse event induced by pembrolizumab, and pembrolizumab withdrawal and prednisolone treatment were performed. Subsequently, her symptoms improved and the follow-up imaging findings showed that the bone lesions had almost disappeared. This case demonstrates that SAPHO syndrome mimicking bone metastases developed during treatment with pembrolizumab. SAPHO syndrome is rare and bone lesions related to the disease may be misdiagnosed as bone metastases. Therefore, it is important in the future for various physicians to have a better understanding of SAPHO syndrome and to consider the potential relationship between this disease and immunotherapy.
Highlights
Non-small cell lung cancer (NSCLC) encompasses 85% of total lung malignancies, which remains to be the leader malignancy worldwide, accounting more than 1.8 million of deaths in 2020 [1]
SAPHO syndrome, first identified in 1987 by Chamot et al is a disorder of unknown aetiology that is manifested by synovitis, acne, pustulosis often on the palms and soles, hyperostosis and osteitis [10]
Uptake in the sternoclavicular region shown in bone scintigraphy is characteristic of the SAPHO syndrome [11]
Summary
Non-small cell lung cancer (NSCLC) encompasses 85% of total lung malignancies, which remains to be the leader malignancy worldwide, accounting more than 1.8 million of deaths in 2020 [1]. The patient was a 69-year-old woman with a history of smoking who received cisplatin and gemcitabine as first-line chemotherapy for stage IV squamous cell lung cancer with abdominal lymph node metastasis but no bone metastasis Her cancer temporarily disappeared due to the effects of first-line chemotherapy; the lymph node metastasis recurred 7 months later and she received second-line chemotherapy with pembrolizumab. MRI was performed to closely evaluate the vertebral lesions, showing multiple bone lesions with a hypointense area on T1-weighted images and contrastenhancing effects on contrast T1-weighted images (Figure 3) These multiple vertebral lesions had a characteristic pattern of SAPHO syndrome showing a semi-circular pattern of contiguous vertebral body involvement localised at the anterior vertebral corners, unlike the usual bone metastases. The patient has remained cancer-free, about 3 years after pembrolizumab withdrawal; she continues to be medicated prednisone due to joint pain
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