Permeative Bone Lesion: Differential Diagnosis #9

While not highly common, a permeative bone lesion is an important finding to note on any study which includes osseous structures. When any bone lesion is encountered, especially a lucent or lytic one, it is important to note the margin, which is also called the zone of transition. If the zone can be easily traced with a pencil, it is called narrow. If it is difficult to make out where abnormal bone ends and normal bone begins, the zone is called wide. The term permeative implies a lesion with a wide zone of transition and multiple small lytic areas within it. This appearance is considered aggressive until proven otherwise. Common permeative lesions can be recalled by the word POLLEN:

	Disease	Notes
P	Permative	Had to make the mnemonic work...
O	Osteomyelitis	Most common: Staph
L	Langerhans Cell Histiocytosis	Spectrum: EG (isolated, benign); Hand-Schuller-Christian (systemic, manageable); Letterer-Siwe (poor px)
L	Leukemia/Lymphoma
E	Ewing's Sarcoma	A small round blue cell / PNET tumor; called Askin when in chest wall
N	Neuroblastoma mets	Primary typically in adrenal, but can be anywhere