CIM Case: Langerhans Cell Histiocytosis - Eosinophilic Granuloma

Clinical Scenario

Patient: 7-year-old boy Presentation: Localised skull pain and tender swelling over the right parietal region for 3 weeks, worse at night, mild irritability Relevant history: Previously well, no weight loss, no polyuria/polydipsia, normal development, no family history of malignancy Examination findings:

3cm tender, non-mobile swelling over right parietal bone
No overlying skin changes
No lymphadenopathy
No hepatosplenomegaly
No skin rash or petechiae
No exophthalmos
Neurologically intact
No other bony tenderness

Investigations Provided

Laboratory Results

Test	Result	Normal Range	Interpretation
Haemoglobin	125 g/L	115-145	Normal
WCC	8.2 x 10⁹/L	5-13	Normal
Platelets	280 x 10⁹/L	150-400	Normal
ESR	25 mm/hr	0-10	Mildly elevated
CRP	8 mg/L	<5	Mildly elevated
LDH	180 U/L	120-300	Normal
ALP	220 U/L	150-400	Normal (child)
Albumin	42 g/L	35-50	Normal
LFTs	Normal	-	No liver involvement
Urine osmolality	650 mOsm/kg	500-800	Normal (no DI)

Imaging

Image 1: Skull X-ray (AP and Lateral)

Radiological features:

Well-defined, punched-out lytic lesion in right parietal bone
Size approximately 3 x 2.5 cm
Geographic bone destruction
No sclerotic rim
"Bevelled edge" appearance (outer table more affected than inner)
No periosteal reaction
No soft tissue calcification
No other skull lesions visible

Image 2: CT Head with Bone Windows

CT findings:

Sharply marginated lytic lesion
Destruction of both inner and outer tables
Bevelled margins confirming asymmetric involvement
Soft tissue component extending into subgaleal space
No intracranial extension
No dural involvement

Image 3: Skeletal Survey

Findings:

No other bony lesions identified
Normal spine (no vertebra plana)
Normal pelvis and long bones
Unifocal disease confirmed

Questions & Model Answers

What is the likely diagnosis and describe the spectrum of this disease?

What investigations would you perform to stage this patient?

What histological findings would confirm the diagnosis?

How would you manage this patient with unifocal skull LCH?

What if this patient had vertebral involvement with vertebra plana?

What features would indicate multisystem disease and how would management change?

Key Teaching Points

Pattern Recognition

This pattern suggests Eosinophilic Granuloma (Unifocal LCH):

Child aged 5-15 years
Punched-out lytic lesion without sclerotic margin
Bevelled edge on skull (pathognomonic)
No periosteal reaction
Single lesion on skeletal survey
No systemic symptoms

Distinguish from Other Lesions:

Feature	LCH	Osteomyelitis	Ewing Sarcoma
Age	5-15 years	Any	10-20 years
Margin	Punched-out	Ill-defined	Permeative
Periosteal reaction	Minimal	Aggressive	Onion-skin
Soft tissue mass	Small	Abscess	Large
Systemic symptoms	Rare	Fever, malaise	B symptoms

Critical Management Points

Skeletal survey is ESSENTIAL - bone scan misses 30% of lesions
Screen for diabetes insipidus - urine osmolality in all patients
Unifocal lesions often self-resolve - especially after biopsy
Intralesional steroids are first-line - for persistent lesions
Vertebra plana reconstitutes - avoid surgery when possible
CD1a + S100 positive - confirms diagnosis

Common Examiner Follow-ups

Q: "Why does bone scan miss LCH lesions?"

LCH lesions are often "cold" on bone scan because:

Rapid bone destruction outpaces osteoblastic response
Bone scan relies on osteoblastic activity for uptake
Skull lesions particularly prone to false negatives
Up to 30% of lesions missed on bone scan

Therefore, skeletal survey (plain X-rays) is the preferred staging modality.

Q: "What is the role of chemotherapy in LCH?"

Indication	Agents
Not indicated	Unifocal bone lesion
Indicated	Multifocal bone disease
Indicated	Any multisystem involvement
First-line	Vinblastine + prednisolone x 12 months
Salvage	Cladribine, cytarabine

Q: "What are the late effects of LCH?"

Late Effect	Incidence	Management
Diabetes insipidus	15-25%	DDAVP lifelong
Growth hormone deficiency	10%	GH replacement
Orthopaedic sequelae	20%	Usually mild
Hearing loss	10-15%	If temporal bone involved
Neurodegenerative disease	1-4%	Cerebellar, rare

Q: "Can LCH recur?"

Disease Type	Recurrence Rate	Notes
Unifocal	10-15%	Usually another bone lesion
Multifocal	30-40%	May need prolonged therapy
Multisystem	50-60%	May need salvage chemotherapy

Recurrence is most common within 2 years of diagnosis. Follow-up should continue for at least 5 years.

Bone Tumours in Children
Paediatric Spine Tumours
Vertebra Plana Differential
Skeletal Survey Indications
Ewing Sarcoma
Osteomyelitis

Langerhans Cell Histiocytosis - Eosinophilic Granuloma