Histiocytosis X

Letterer-Siwe Disease

·       10% of histiocytosis X
·       Acute disseminated, fulminant form
·       Age at onset

o      Several weeks after birth to 2 years

·       Pathology

o      May be confused with leukemia

·       Symptoms

o      Hemorrhage, purpura

o      Severe anemia

o      Fever

o      Hepatosplenomegaly and lymphadenopathy

·       Bone involvement in 50%

o      Widespread lytic lesions

·       Prognosis: 70% mortality rate  

Hand-Schuller-Christian  

·       15-40% of Histiocytosis X

·       Triad of:

o      Exopthalmus (33%)

o      Diabetes insipidus (30-50%)

o      Lytic skull lesions

·       Pathology

o      May simulate Ewing's sarcoma

·       Age at onset

o      5-10 years

·       Target organs

o      Bone
§       Lytic skull lesions with overlying soft tissue nodules
§       Large geographic skull lesions
§       "Floating teeth" with mandibular involvement

o      Soft tissue
§       Hepatosplenomegaly is rare
§       Lymphadenopathy which may be massive

o      Lung
§       Cyst and bleb formation with spontaneous PTX
§       Ill-defined diffuse nodular disease often leading to
fibrosis and honeycombing

·       Prognosis: spontaneous remissions and exacerbations  

Eosinophilic granuloma  

·       60-80% of Histiocytosis X

·       Usually confined to bone

·       Age at onset

o      5-10 years highest frequency

o      Male predominance 3:2

·       Location

o      Calvarium>mandible>spine>ribs>long bones

o      Most are monostotic (50-75%)

·       Target organs

o      Skull (50%)
§       Diploic space of parietal bone most often
§       Round or ovoid punched out lesions with beveled edge
§       Sclerotic margin during healing phase
§       Beveled edge=hole-within-a-hole
§       Button sequestrum- bony sequestrum within lytic lesion
   §       Axial skeleton (25%)

o      "Vertebra plana"-"coin-on-edge" (Calve disease)=collapse
of vertebral body, mostly thoracic

§       Most common cause of vertebra plana in children

o      Proximal long bones (15%)
§       Expansile, lytic lesions, mostly diaphyseal
§       Soft tissue mass
§       Laminated periosteal reaction

o      Lung (20%)
§       Age peak between 20-40 years
§       Multiple small nodules
§       Predilection for apices
§       Prototype for honeycomb lung
§       Recurrent pneumothoraces (25%)
§       Rib lesions with fractures common

·       Nuclear Medicine

o      Negative bone scans in 35%

o      Bone lesions usually not Ga-67 avid

o      Ga-67 may be helpful in detecting non-osseous lesions

·       Prognosis: excellent

Eosinophilic Granuloma of the Lung. There are multiple, thin-walled cystic structures, greater in the
upper than the lower lobes, characteristic of this disease.