The present study describes the case of an 18-year-old adolescent male exhibiting acute lymphocytic leukemia (ALL), complicated by the onset of the symptom of sacroiliitis mimicking spondyloarthritis. Atypical features including an enlarged spleen, poor effects of non-steroidal anti-inflammatory drug therapy, low levels of hemoglobin, a low platelet count, a low neutrophil count and increased levels of monocytes, indicated the possibility of hematological malignancy. Bone marrow examination confirmed the diagnosis of ALL. The patient received chemotherapy and the symptoms were dramatically relieved. To the best of our knowledge, the current study reports the second published case of a patient with ALL presenting with sacroiliitis. Sacroiliitis as an onset manifestation of ALL may result in misdiagnosis, therefore, a differential diagnosis is essential when atypical features are present.
Keywords: acute lymphocytic leukemia; paraneoplastic syndrome; sacroiliitis; spondyloarthritis.