The disorders of xanthohistiocytic proliferation involving histiocytes,
foam cells, and mixed inflammatory cells are divided into Langerhans
cell histiocytosis (LCH) and non-Langerhans cell histiocytosis (non-LCH).
Histiocytosis (Histiocytosis X)
LCH is an idiopathic spectrum of disorders characterized by a
clonal proliferation of Langerhans cells. Clinically, LCH is characterized
by lytic bony lesions and cutaneous findings that range from soft
tissue swelling to eczema- and seborrheic dermatitis-like skin changes
Histiocytosis can be extremely difficult to diagnose. In infants
with diaper rash that will not heal, particularly if there are erosions
in the folds or petechiae/purpura, histiocytosis should
Synonyms Class I histiocytosis,
nonlipid reticuloendotheliosis, eosinophilic granulomatosis.
LCH has four overlapping forms:
1. Letterer–Siwe disease: aggressive LCH
with diffuse skin and organ infiltration and thrombocytopenia
2. Hand-Schüller-Christian disease: LCH with lytic skull
lesions, exophthalmos, and diabetes insipidus
3. Eosinophilic granuloma: single osteolytic bony lesion ± skin/soft
4. Hashimoto–Pritzker disease: congenital self-healing
Age Any age, common 1 to 3 years.
Incidence Rare, 5/million
Genetics Familial case reports.
The proliferating Langerhans cell appears to be primarily responsible
for the clinical manifestation of LCH. The stimulus for the proliferation
may be a disturbance of intracellular lipid metabolism, a reactive
response to infection (?viral), a primary immunologic disorder of
the host, or an inherited neoplastic disorder.
LCH has a broad clinical spectrum, but in the most aggressive
form (Letterer–Siwe disease), the infant appears systemically
ill with a generalized skin eruption (seborrhea, petechiae, and
purpura) followed by fever, anemia, thrombocytopenia, adenopathy,
hepatosplenomegaly, and/or skeletal lesions.
Type Papules, plaques, vesicles,
scale, petechiae, purpura, ulceration, necrosis.
Color Pink, flesh-colored.
Distribution Flexural areas: neck,
axillae (Fig. 19-1), and perineum > trunk (Fig. 19-2).
Histiocytosis X Erythematous
plaques with ulceration and maceration in the axilla of an infant.
Langerhans cell histiocytosis Erythematous
papules and a crusted, purpuric plaque on the abdomen of an infant.
Fever Lymphadenopathy (LAD). Ill
Pulmonary Infiltrate disease of
the lung bases and midzones, pneumothorax.
Bone Osteolytic lesions: calvarium,
sphenoid bone, sella turcica, mandible, long bones of upper extremities