[poikilos, Greek = mottled]

= OSTEOPATHIA CONDENSANS DISSEMINATA

= rare autosomal dominant sclerosing bone dysplasia ← disorder of endochondral ossification involving the secondary spongiosa characterized by multiple bone islands / enostoses

Age: no age predilection (may not develop until after childhood); M = F

Histo: hamartomatous foci of lamellar cortical bone within dense trabeculae of spongy bone / inner bone cortex = compact bone islands

Genetics: inactivating mutation in LEM domain–containing protein 3 gene (LEMD = protein that antagonizes transforming growth factor (TGF)–b and bone morphogenic protein signaling focal deposits of compact lamellar bone in spongiosa

Associated with:

• Dermatologic disorders:
  1. Dermatofibrosis lenticularis disseminata (Buschke-Ollendorff syndrome) = asymptomatic small flesh-colored to yellow dermal papules / coalescent plaques (in 25%) on buttocks, trunk, arms, skin folds
     Age: usually in childhood; often in 1^st year of life
     Histo: connective tissue nevi with predominantly abnormal elastin / abnormal collagen
  2. Scleroderma
  3. Keloid formation
• Bone abnormalities:
  1. Melorheostosis
  2. Osteopathia striata
  3. Synovial chondromatosis
  4. Rheumatoid arthritis

• commonly asymptomatic
• mild articular pain + joint effusion (15–20%)

Site: metaphyses + epiphyses (rarely extending into midshaft)

Location: long tubular bone epiphysis / metaphysis; hand (carpal + metacarpal), foot (tarsal + metatarsal), ankle, pelvis (glenoid + acetabulum), scapula; rare in skull, ribs, vertebral centra, mandible

• multiple round / ovoid / lenticular bone islands (2–10 mm) in an often symmetric distribution:
  • long axis of lesions parallel to long axis of bone
  • may increase / decrease in size and number
  • may disappear
• bone scintigraphic activity usually normal / mildly increased (similar to bone island / enostosis)
• MR signal characteristics equal to cortical bone

Prognosis: not progressive, no change after cessation of growth

DDx:

1. Epiphyseal dysplasia (metaphyses normal)
2. Melorheostosis (diaphyseal involvement)
3. Mastocytosis
4. Tuberous sclerosis
5. Osteoblastic metastases