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Page 7 / Case 09/02

DIAGNOSIS of HISTIOCYTOSIS

1) Birbeck granules that are a pentalaminar 5-layered rod shaped structure seen on electron microscopy.

2) Staining with S-100 Protein

3) Staining with CD1a antigen on the cell surface

Langerhans Cell Histiocytosis Classification:
Many classifications based on single organ involvement vs. multisystem disease. Single organ involvement may include bone, or lung (eosinophilic granuloma). Single bone is the most common organ presenting. Multi system involvement can be limited or disseminated. Limited multi system involvement includes skin, bone, or CNS (Diabetes Incipidous), vs. dissemination to and including lung, liver, and spleen or haematological involvement.
Older terminology including Systemic Histiocytosis X (eosinophilic granuloma ), Letterer-Siwe Disease (visceral disease with multiple organs), Hans-Schuller Christian disease( triad of skull defects, diabetics incipidous, exophthalmos) is no longer commonly used.

Mortality
Pulmonary involvement with opportunistic infections is the most common cause of death. Pneumocystis Carinii Pneumonia prophylaxis is recommended for all patients actively treated. In adults the mortality is higher is smokers. Pulmonary involvement is seen is 33-72% of disseminated cases. All case reports of isolated pulmonary histiocytosis also had severe failure to thrive.

Role of PFT in LCH
Most common abnormalities are 1) DLCO 2) Lung Compliance Lung Volumes are low with mixed restriction and obstruction. Pulmonary function abnormalities often precede clinical signs and symptoms. Role of Bronchoalveolar lavage in pediatric LCH: Bal fluid abnormalities precede clinical symptoms. More than 5% CD-1 positive cells are seen via the immunoperoxidase method. In adults it can be differentiated from sarcoid < 3.6 % CD positive cells. Smoking in adult studies is not influential on CD-1 positivity. Radiological Abnormalities: Early: diffuse micronodular pattern Over Time: cysts progressing to honeycombing lung Late: severe emphysems and bullae Distribution: upper lobes/perihilar areas with sparing of costrophrenic angles. Rarely mediastinal adenopathy.



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