Imaging of Histiocytosis in the Era of Genomic Medicine

Abstract

■ Describe the novel genomic discoveries of histiocytosis and their implications for radiologic interpretation and patient management. ■ Discuss the role of imaging in diagnosing and monitoring histiocytosis in the new era of precision medicine approaches for treatment. ■ Recognize the imaging characteristics of common and uncommon subtypes of histiocytosis with a focus on adult-onset cases.

The added value of skeletal surveys in the initial evaluation of children diagnosed with Langerhans cell histiocytosis in the era of staging 18F‐FDG PET/CT: A retrospective study

“…Because of the varying severity and organs of involvement, the clinical presentation of LCH ranges from an asymptomatic solitary bone lesion to a multisystem life‐threatening condition 7,10,11 . This diverse pattern of disease manifestation in LCH translates into a broad spectrum of imaging findings 12,13 . LCH can affect any age but tends to be more severe and multisystemic in the younger patient population 6–8,14 .…”

“…Based on these considerations, accurate staging of LCH is necessary for risk stratification and optimal treatment planning, ranging from conservative treatment for most cases of SS-LCH to chemotherapy for MS-LCH. 13,16,17 Imaging plays an important role in staging of LCH. Various imaging modalities had been employed in the past, including skeletal survey, 99m Tc-methylene diphosphonate (MDP) bone scan, whole-body magnetic resonance imaging (MRI), and 2-deoxy-2-[fluorine -18] fluoro-D-glucose integrated with computed tomography (FDG PET/CT).…”

“…7,10,11 This diverse pattern of disease manifestation in LCH translates into a broad spectrum of imaging findings. 12,13 LCH can affect any age but tends to be more severe and multisystemic in the younger patient population. [6][7][8]14 Based on a population study, the estimated minimum annual incidence of LCH is 8.9 per 1,000,000 children under 15 years of age.…”

“…MS‐LCH is further subdivided into low‐risk groups, including those without involvement of risk organs such as liver, spleen, and hematopoietic system (MS‐RO−), and high‐risk groups, including those with risk organ involvement (MS‐RO+). Based on these considerations, accurate staging of LCH is necessary for risk stratification and optimal treatment planning, ranging from conservative treatment for most cases of SS‐LCH to chemotherapy for MS‐LCH 13,16,17 …”

FDG PET/CT in Mixed Langerhans Cell Histiocytosis and Erdheim-Chester Disease

“…This helped establish the additional diagnosis of Erdheim-Chester disease (ECD), which has cardiovascular involvement in at least 50%, most commonly pericardial infiltration and effusion, and retroperitoneal fibrosis in 33% of cases. 1,2 Table 1 summarizes the most common age of onset, most frequent organs involved, immunohistochemistry, and frequency of BRAF V600E mutations in LCH [3][4][5][6] and ECD, 3,7,8 and compares these with our patient. With ECD, 20% of patients have LCH, which can be at the same biopsy site in 30% of cases.…”