Langerhans cell histiocytosis (LCH) is a rare, poorly understood disease. Despite LCH being considered a non-hereditary disorder, a subset of LCH is familial [5]. Currently, neoplastic or inflammatory disease is primarily accused with predisposing factors [1, 6]. Although it can be seen in any age group, it mostly occurs in childhood. The median age at diagnosis is between 1 and 4 years of age.

It is slightly more common in boys than girls. The clinical picture can range from solitary or multifocal bone lesions to common diseases with multiorgan involvement [1]. Temporal bone involvement is seen in 15-60% of cases, and bilateral involvement is seen in 25–30% of cases. In addition to the temporal bone, the head and neck area may be involved, including the orbital bone, mandible, scalp, maxillary bone, and facial skin. Clinical findings vary depending on the location. Therefore, LCH has no specific symptoms [7]. It involves the most common mastoid process in the temporal bone and can easily spread to the middle and outer ear.

Otological findings are similar to otitis media, otitis externa, and cholesteatoma [1]. This diversity in clinical appearance may mislead the physician. Misdiagnosis rate increased to 72.7% [8]. LCH can often be confused with acute otitis, chronic otitis, and its complications, which are unresponsive to treatment and more common in children. This situation causes a delay in diagnosis and treatment. The most common otological symptoms are otorrhea, swelling in the mastoid region, external ear canal polyp, and hearing loss. Conductive or mixed hearing loss is common. Sensorineural hearing loss is rarely seen due to cochlear damage and bone erosion in the internal auditory or semicircular canals [3].

Clinical presentation should be investigated in detail along with imaging methods. Laboratory examinations are required in cases with multiple system involvement (complete blood count, coagulation, and liver function tests). Radiologically, a bone scan is required. Typically, widespread lytic lesions with well-defined soft tissue edges appear without sclerotic margins [9]. High-resolution CT (HRCT) is preferred to evaluate temporal bone involvement and to monitor treatment response. In HRCT, it is typically seen as sharp ‘beveled edges’ lytic lesions associated with soft tissue mass. However, only findings related to the infectious process can be seen in some cases [10]. Diagnosis with MRI without CT may be overlooked [6]. On MRI, LCH lesions were typically found to be hypointense on T1- and isointense to hyperintense on T2-weighted images with avid gadolinium uptake [2]. Definitive diagnosis requires lesion biopsy for histopathological examination. Birbeck granules are observed with electron microscopy. LCH cells stain positively with antibodies to S100, CD1a, and/or CD207/Langerin. Staining with CD1a or CD207/Langerin confirms the diagnosis of LCH. CD-207/Langerin is crucial for the diagnosis since it can be an indicator of the presence of Birbeck granules. Also, the BRAF mutation is found in more than 50% of LCH cases. However, the allele frequency is very low. This may therefore lead to frequent false-negative molecular results if sensitive methods are not employed.

There are several treatment options available after diagnosis, including surgery, chemotherapy, radiotherapy, intralesional steroid injection, and targeted therapy. These can be used alone or in combination depending on the extent, grade, and severity of the disease [11,12,13]. While surgery is preferred in a single-system disease, chemotherapy is used in multisystem diseases. Radiotherapy is no longer recommended for the treatment of temporal bone LCH [1]. In this case, the pediatric hematology and oncology department used chemotherapy and steroids after diagnosis due to multisystem presentation. The patient did not have any complaints during the 7-year follow-up, and her annual controls continue. The patient is followed by direct radiographs.

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