Langerhans cell histiocytosis of the mastoid

Case contributed by Dr Alasdair Grenness

Presentation

Two weeks of left otalgia, discharge and polyp protruding through the external auditory meatus.

Patient Data

Age: 15 years
Gender: Female

At presentation to the emergency department the patient was otherwise well but found to have a polyp herniating out of the left external auditory meatus with purulent discharge without mastoid tenderness. The patient had a past history of previous middle ear ventilation tubes insertion around 5 years ago. A dry perforated right tympanic membrane was also noted. Facial nerve function remained intact. 

The patient proceeded to an examination under anesthesia the next day. The limits of the polyp could not be identified and the tympanic membrane could not be visualized. Biopsy of the polyp noted it to be more vascular that typical inflammatory polyps seen in otitis externa or cholesteatoma. The patient subsequently proceeded to CT scanning. 

There is a soft tissue destructive mass centered on the left mastoid and sigmoid region roughly 18 x 19 x 30 mm in size. There is associated bony erosion and the epitympanum is opacified but the scutum is intact. The ossicular chain and bony labyrinth appear unaffected. The external auditory canal is completely opacified.  

Given the extent of destruction the patient proceeded to urgent MRI. 

There is a soft tissue mass centered on the left mastoid region. There is high signal and heterogeneity on the T2 intermediate and avid, but heterogeneous, enhancement post-contrast. There is enhancement of tissue in the mastoid antrum and epitympanum extending inferiorly to the mastoid tip. 

Medially the mass looks to be contained by the dura and there is separation of the sigmoid sinus. Given the high signal within the sigmoid sinus on T2 signal with enhancement post contrast there is likely slow flow through rather than thrombus. 

Comment: In this age group, the most likely cause is Langerhans cell histiocytosis.

Histopathology revealed inflamed granulation tissue with numbers of neutrophils. Review of the biopsy after further history of a large destructive bone lesion showed that the macrophages in the infiltrates were reactive for CD1a and S100-protein consistent with Langerhans cell histiocytosis.

The patient was subsequently transferred to a tertiary pediatric center, whereby isolated disease was confirmed on PET scanning and systemic treatment was instigated. 

Slide 1: Langerhans histiocytes associated with neutrophils and eosinophils.

Slide 2 & 3: CD1a and S100 protein immunohistochemistry shows the Langerhans cells.

With thanks to Associate Professor Penny McKelvie. Neuropathologist, Anatomical Pathology. St Vincent’s Hospital. East Melbourne. Victoria. Australia.  

Case Discussion

Langerhans cell histiocytosis (LCH) is characterized by the proliferation of mononuclear cells resulting in granulomatous lesions. Patients may present with isolated or systemic disease 1

Bone lesions are the most common manifestation of LCH radiologically occurring in around 80% of patients. Most commonly LCH affects flat bones with the skull being the most common site involved followed by mandible, ribs, pelvis and spine 2

Skull involvement commonly reveals a well defined lytic "punched-out" appearance due to asymmetrical destruction of the inner and outer cortices on CT or x-ray. Magnetic resonance imaging reveals a soft tissue component commonly hyperintense on T2 weighted images, isointense of T1 weighted images and enhances post-contrast 2

Ear involvement occurs in 15% of cases and may present with otorrhea, mastoid swelling, external auditory canal (EAC) polyps, or cholesteatoma. Treatments include surgical or systemic options 1,3.

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