Microgeodic phalangeal syndrome is a rare condition affecting the fingers in children. Radiographically, the affected phalanges show sclerosis with multiple small areas of osteolysis. The pathogenesis of microgeodic phalangeal syndrome is considered to be a transient disturbance of the peripheral circulation caused by cold temperatures. In most cases, the symptoms and the radiographic changes return to normal within several months without any treatment. We present a rare case of microgeodic phalangeal syndrome in the middle phalanx of the right index finger in an 8-year-old girl, in whom the affected phalanx shortened within 6 weeks of the initial presentation. It was speculated that minor trauma to the finger might have contributed to the collapse and shortening of the phalanx. The current case indicates that the use of a splint for the affected finger in the early period after onset of symptoms might be recommended to avoid digital shortening.