Relevance of Bone Scintigraphy in the Diagnostic Algorithm for Examining Treatment-Naive Pediatric Patients with Langerhans Cell Histiocytosis: a Retrospective Cohort Study

Abstract

Background. Histiocytosis is a heterogeneous group of rare diseases of unknown etiology. Langerhans cell histiocytosis (LCH) is characterized by an abnormal proliferation of histiocytes (activated dendric cells and macrophages). LCH is the most common form of histiocytosis, it is a potentially fatal diseases. Early detection of LCH plays an important role in its prognosis and outcome. However, the role of advanced methods of nuclear medicine in diagnosis of LCH is still to be researched. We have long-term experience in observing pediatric patients with LCH. Taking into the account the difficulty of diagnostic task for bone scintigraphy in identifying lytic bone destruction, we stated the following objective of the study. Objective. Our aim was to perform retrospective analysis of bone scintigraphy examinations of treatment-naive pediatric patients with LCH and calculate the diagnostic efficacy of bone scintigraphy. Methods. We retrospectively analyzed 55 examinations of treatment-naive pediatric patients (the median age was 5.9 years) with proven case of LCH (2014–2018). Results. During examination we visualized 82 lesions with pathological level of accumulation of radiopharmaceutical in 55 patients. 78 with high level of accumulation (>120%); 3 with slightly increased level of accumulation (100–120%) and 1 with lower than normal level of accumulation (<100%). The median level of accumulation of radiopharmaceutical was 276%: max. level of accumulation was 1422% (patient with subtotal involvement of femoral bone), min. — 60% (patient with lytic destruction in orbital bone). During X-Ray we found out 91 pathological focuses of bone lytic destruction. In 3 patients with polyostotic form we found extra focuses on scintigraphy, which were confirmed with following examination and X-Ray. 8 lesions were not found on scintigraphy in 8 patients. Сonclusion. Bone scintigraphy with 99mTc-MDP in treatment-naïve pediatric patients with proven case of LCH showed sensitivity — 91.0%, specificity — 50.0%, NPV — 11.1%, and PPV — 98.8%.