Langerhans Cell Histiocytosis (LCH) - Eosinophilic Granuloma😊

Langerhans Cell Histiocytosis (LCH) - Eosinophilic Granuloma

Definition

• Rare disorder with excessive proliferation of Langerhans cells (dendritic cells),
• causing granulomatous lesions in various organs.

• Due to clonal proliferation of CD 1a or CD 207.

Epidemiology

• Age: Primarily 1-15 years; peak 1-3 years.

• Sex: Slight male predominance (1.5:1).

Clinical Features

Single-system LCH:

• Bone:
• Osteolytic bone lesions (punched out lesions),
• Painful
• fractures (skull, ribs, femur, pelvis).
• skull & mastoid involved
• chronic ear discharge.

• Skin:
• Seborrhea,
• Scaly papules, eczematous rash, or nodules (infants).

• Lymph nodes:
• Cervical lymphadenopathy.

Multisystem LCH:

• Liver/Spleen:
• Hepatomegaly, dysfunction.

• Bone marrow:
• Pancytopenia
• extramedullary hematopoiesis
• hepatosplenomegaly.

• Lungs:
• Cysts, nodules
• Pneumothorax,
• pleural effusion

• Central nervous system:
• Pituitary involved
• Diabetes insipidus
• GH deficiency.
• neurodegenerative changes.

• High-risk organs (liver, spleen, bone marrow):
• Poorer prognosis.

Diagnosis

Biopsy:

• Gold standard
• CD1a, CD207 (langerin),
• S100 positive

• Electron microscopy:
• Tennis racket-shaped Birbeck granules.

Tennis Racket Appearance

 

Condition	Context / Type
Rhabdomyosarcoma	Skeletal muscle tumor
Langerhans cell histiocytosis	Seen on electron microscopy
Giardia lamblia	Parasite (microbiology)
Clostridium tertium	Bacteria (not tetani)

SKULL XRAY PATTERN APPROACH

Imaging:

• X-ray/CT:

• Head
• Lytic bone lesions, “punched-out” appearance, without sclerotic rim
• Hole within a hole sign:
• Double contour bevelled edge appearance
• Button sequestra representing residual bone
• Geographic skull

• Mandible
• Floating tooth

• Spine
• Vertebra plana (most common cause in children, in thoracic spine)

• MRI: CNS, soft tissue.

• PET-CT: Staging, extent.

Lab Tests:

• CBC: Anemia, thrombocytopenia.

• Liver function tests: Elevated (hepatic involvement).

• Urine osmolality: Diabetes insipidus.

• BRAF V600E mutation: ~50-60% cases; guides therapy.

Staging

• Single-system:
• One organ/system (unifocal/multifocal).

• Multisystem:
• Low-risk: No high-risk organs.
• High-risk: Involves liver, spleen, bone marrow.

Treatment in LCH

• Curettage/excision (unifocal) in bone lesions

• Observation (asymptomatic).

• BRAF inhibitors:
• Vemurafenib
• Dabrafenib (off-label).
• Mnemonic: “Raf Nib” → bRAF inhibitors

• Localized:
• Intralesional steroids:
• Methylprednisolone 40-80 mg
• Radiation
• Curettage

• Multifocal:
• Chemotherapy:
• Vinblastine + Prednisone ± Mercaptopurine.