| • | AKA Langerhans Cell Histiocytosis |
| • | the disseminated form is seen almost exclusively in children <3 years old |
| • | the localized forms are more common in older children |
| • | = dendritic cells in the epidermis which are of mesenchymal lineage by way of bone marrow derived precursors |
| • | Birbeck granules (tennis rackets) seen with electron microscopy; represents invaginations of the cell membrane |
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clinical:
Skin lesions may comprise any combination or all of the following:
| • | crusting of the scalp (suggesting seb derm) |
| • | ulcerated granulomatous lesions of the buccal mucosa or inguinal, perineal, or vulvar lesions |
| • | scaly, rose-yellow, reddish brown papules (location: scalp, especially above and behind ears, “seborrheic areas”, perineum, palms and soles) |
| • | erosive intertrigo; perianal erosions |
| • | erosions and purpuric lesions (thrombocytopenia secondary to bone marrow invasion) |
| • | IN GENERAL, an unusual or recalcitrant diaper rash should alert the physician to consider the diagnosis (the presence of petechiae or palm/sole lesions are particularly helpful signs) |
systemic findings:
| • | hepatosplenomegaly, lymphadenopathy, diffuse pulmonary infiltrate, bone lesions, pancytopenia |
| • | other findings: buccal and gingival ulcerations, chronic recurrent otitis media |
| • | death if untreated (treatment: chemotherapy or bone marrow transplant) |
differential diagnosis:
| • | leukemia / HIV (the whole picture) |
| • | candidal diaper dermatitis |
| • | streptococcal perianal dermatitis |
clinical forms (spectrum):
| • | the acute disseminated form of the disease |
| • | often infants <3 years old |
| • | in infants, vesicular or crusted papules may predominate |
| • | purpura of the palms – a finding seldom seen in other skin diseases; poor prognosis |
| • | in general, implies a fatal outcome, though coarse varies and may evolve into a more chronic phase such as Hand-Schuller-Christian |
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| 1. | bone lesions (osteolytic defects)* |
| • | *xray = geographic skull (sharply defined areas of osseus rarefaction) |
| • | erosion of tooth bearing portion of mandible with loosening or extrusion of teeth |
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| • | consists of a solitary bone lesion; strong tendency to spontaneous remission |
| • | often goes undetected until a spontaneous fracture or incidental xray |
| • | skin lesions relatively rare |
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| • | lesions present at birth as papules and nodules |
| • | spontaneously resolve with 2 to 3 months |
| • | confined to skin and mucous membranes (i.e. no systemic involvement) |
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