A case of osteopoikilosis: Low back and bilateral knee pain

Osteopoikilosis (OPK) is a very rare benign sclerosing bone dysplasia of unknown etiology. OPK has been documented recently as an inherited autosomal disorder that results from functional loss of the LEMD3 gene. OPK has often been misdiagnosed as bone metastasis because it is characterized radiologically by multiple, small, roundish or ovoid foci of bony sclerosis. OPK is usually asymptomatic, but 15~20% of patients have joint pain, and 25% present with cutaneous lesions. This case report describes a 19-year-old man who suffered from low back pain and bilateral knee pain with intermittent effusion.