Solitary bone cyst of the pelvis is a rare lesion. The diagnosis is relatively simple providing sufficient material is accumulated during biopsy or surgery. Calcifying forms often cause difficulties in terms of differential diagnosis. Radiographic imaging can be complex when examining large lesions of the pelvis. Biopsy is the method of choice for definitive diagnosis, which should be verified against material gathered surgically or during curettage. Bone tumors of the pelvis have to be considered in the differential diagnosis of the lesion. Large cystic lesions of the pelvis in particular are to be reviewed pathohistologically to avoid false diagnosis. The consequences for the patient in terms of quality of life and life expectancy can be serious. The need for interdisciplinary cooperation is greater than ever to ensure correct diagnosis and therapy of bone lesions.