Musculoskeletal mnemonics: differentiating features.

Mnemonics are often used in musculoskeletal radiology to help radiologists remember long differential diagnoses. However, unless the specific appearance of each entity on a differential is also recalled, mnemonics become useless. This article presents 8 mnemonics with their corresponding differential diagnoses and distinguishing features. Bubbly lucent lesions of bone are recalled with the FEGNOMASHIC mnemonic, but when only lucent lesions of the diaphysis are included, a more appropriate mnemonic is FEMALE. The lucent lesions of bone differentials often can be narrowed based on specific characteristics of the lesion but radiographic findings elsewhere and clinical information often help. Osseous metastases may present as lucent or sclerotic lesions; when sclerotic, the differential is best remembered with the mnemonic 5 "BEES" Like Pollen. The mnemonic for Wormian bones is PORKCHOPS. The Wormian bones in most of these entities are indistinguishable, so one must rely on radiographic findings outside the skull for diagnosis. By contrast, differentiating causes of acro-osteolysis is often possible with findings seen only on the hand radiographs; the mnemonic for acro-osteolysis is RADSHIP. In skeletally immature patients with frayed metaphyses, the mnemonic is CHARMS. Although the appearance of the fraying is seldom diagnostic, findings in the adjacent portions of the long bones may be characteristic. FETISH is the mnemonic used to remember the entities for the differential diagnosis of vertebra plana. Age of the patient, clinical history, and findings in the adjacent spine often help to provide the specific diagnosis. Nearly all the entities on the differential diagnosis for distal clavicle erosion (mnemonic: SHIRT Pocket) are included in other differentials in this article.