Bilateral Temporal Bone Langerhans Cell Histiocytosis: Radiologic Pearls
A previously healthy 2-year-old girl presented with a ten day history of progressive left-sided postauricular erythema and swelling. She was noted to have clinical worsening while being treated with antibiotics, and was referred to our hospital for further evaluation for acute mastoiditis.\nOn examination, the patient's left ear was protuberant anteriorly from swelling posteriorly. There was overlying erythema and swelling in the postauricular area. This area was very soft, and a bony edge was palpated surrounding the soft area. It was not warm or tender. External auditory canal examination showed the posterior canal wall to be pushed forward, impacting the anterior canal wall. The posterior canal wall had a pink, irregular surface consistent with granulation-like changes. The right ear exam was normal. No skin lesions or ear drainage were noted. Neurologic exam was normal. The remainder of the exam was unremarkable.\nLaboratory studies revealed a mild normocytic anemia (9.8 g/dL; reference range 11.0 to 14.0 g/dL), a mild leukocytosis (11.2 x10(9)/L; reference range 6.0 to 11.0 x10(9)/L), an elevated C-reactive protein (58 mg/L; reference range < 8 mg/L) and erythrocyte sedimentation rate (64 mm/hour; reference range <22 mm/hour).\nThe skull radiograph demonstrated lytic lesions of the bilateral temporal bones (Fig. ). Imaging with computed tomography (CT) revealed bilateral bony erosion of the temporal bone in the petromastoid region, left greater than right, with left-sided extension into the soft tissue (Fig. ). Differential diagnosis based on imaging included unusual otomastoiditis, Langerhans cell histiocytosis, rhabdomyosarcoma, lymphoma, metastasis such as neuroblastoma, or unusual Wegener’s granulomatosis. For further characterization of these lesions and to evaluate for the presence of intracranial extension, magnetic resonance imaging (MRI) was conducted (Fig. ). Again, bilateral temporal bone changes and left sided soft tissue prominence were noted. This extended superiorly, along the tegmen tympani where there was minimal adjacent dural thickening and enhancement without brain parenchymal involvement (Fig. ). These lesions enhanced with gadolinium. Given the sparing of the labyrinth (Fig. and ), the bilaterality, and the overall appearance, the findings were most consistent with LCH.\nDefinitive diagnosis was confirmed with biopsy. Pathology revealed positive immunohistochemical staining for CD1a, which is pathognomonic for LCH. Skeletal survey, CT of the chest, abdomen, and pelvis, and bone marrow biopsy were all negative for signs of further involvement. Audiometry demonstrated left-sided conductive hearing loss.\nUpon diagnosis, the patient proceeded with standard induction therapy including vinblastine and prednisone for six weeks followed by repeat imaging. She had an incomplete response, and thus received a second induction. She then went on to receive continuation therapy with vinblastine and prednisone. Interim imaging with CT (Fig. ) and MRI (Fig. ) has suggested a positive response to therapy with no progression of disease. Additionally, her hearing improved on subsequent audiometry.