Langerhans Cell Histiocytosis-Associated Vertebra Plana on FDG PET

Case Introduction

A previously healthy 10-year-old male presented with 2 weeks of severe, atraumatic neck pain “spreading” to his right arm, waking him nightly. Symptoms persisted despite supportive care and nonsteroidal anti-inflammatories. He described the pain as 9/10, most severe in his upper back and associated with intermittent tingling of his right little finger. Aggravating factors included neck movement, and alleviating factors included elevating his right arm. History was negative for recent injury, fever, chills, weight loss, night sweats, or evidence of neurologic deficits. Patient was afebrile, and the remaining vitals were within normal limits. The physical exam was notable for tenderness at the C7 spinous process without evidence of neurologic deficits.

Cervical spine computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated C7 vertebra plana ([Fig. 1]A, B) with enhancing perivertebral soft tissue ([Fig. 1]C). 2-deoxy-2-[¹⁸F]fluoro-D-glucose (FDG) positron emission tomography (PET) showed intense uptake at that location. The only additional faint radiotracer accumulation included regions of probable brown fat activation, including the bilateral supraclavicular, axillary, and mediastinal fat. Otherwise, no evidence of abnormal uptake identified ([Fig. 1]D). Differential considerations for these imaging findings include Langerhans cell histiocytosis, particularly given the patient’s age, and less likely leukemia/lymphoma, metastatic disease, and infectious etiologies, including mycobacterial infections. Patient subsequently underwent C7 vertebrectomy and tissue sampling. Histologic findings demonstrated fragments of bone with a dense inflammatory infiltrate, and atypical cells. The atypical cells demonstrated large, epithelioid forms with oval nuclei, occasional nuclear grooves, and abundant eosinophilic cytoplasm; some cells demonstrated nuclear atypia. Multinucleated cells were also present. The inflammatory infiltrate comprised of eosinophils, histiocytes, lymphocytes, and plasma cells. Immunohistochemical stains for S100, CD1a, and Langerin stains (CD207) were positive ([Fig. 2], [Fig. 3]), while CD68 was negative in the Langerhans cells. BRAF V600E was negative by immunohistochemistry. The morphologic and immunophenotypic pattern were compatible with the diagnosis of Langerhans Cell Histiocytosis (LCH).

Fig. 1 A Sagittal cervical spine CT demonstrates C7 vertebra plana (red circle). The differential diagnosis in this pediatric patient included LCH, lymphoma/leukemia, and less likely metastatic disease. B Right paramedian sagittal T2 cervical spine MRI demonstrates mild retrolisthesis at C6–C7 with spinal canal narrowing. C Right paramedian sagittal T1 post contrast cervical spine MRI additionally demonstrates enhancing perivertebral soft tissue (red arrow). D Sagittal PET/CT image following administration of 7.79 mCi with an imaging delay of 61 minutes demonstrates marked uptake in the viable tumor involving C7. Otherwise, the only radiotracer uptake demonstrated was favored to be related to brown fat activation.

Fig. 2 A H&E section demonstrates fragments of bone and soft tissue with dense infiltrate of mononuclear and giant cells with a mixed inflammatory infiltrate (100×); B Higher magnification (400×) with prominent inflammatory infiltrate composed of lymphocytes and eosinophils. C Higher magnification (400×) demonstrating multinucleated giant cells admixed with mononuclear cells with occasional indented and coffee bean nuclei (black arrow), consistent with Langerhans cells.

Fig. 3 A H&E section demonstrating a focal area with increased mononuclear cells consistent with Langerhans cells. These cells showed immunoreactivity for CD1a immunostain (B) and Langerin stain (CD207) (C). D CD68 demonstrating negative stain in the Langerhans cells, but positive in the histiocytes and in the multinucleated giant cells. Magnification 400×.

Publication History

Received: 21 September 2024

Accepted: 09 October 2024

Article published online:
27 November 2024

• References

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