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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