Clinical Importance of Lymphocytopenia in Pediatric Head and Neck Lymphatic Malformations

Introduction: Small case series have suggested that lymphocytopenia may be associated with a more aggressive lymphatic malformation (LM) disease course; however, the clinical importance of lymphocytopenia in the setting of LM still remains unclear. The objective of this study was to determine if LM-associated lymphocytopenia was associated with higher rates of antibiotic use and more frequent hospitalizations for infections. Methods: An IRB-approved, retrospective case series review was performed on all patients with the ICD-10 codes corresponding to LM between 2008 and 2018 at a single institution. Patients with a complete blood cell count and lymphocyte differential were included. Lymphocytopenia was defined as <1500/cm3. Variables including LM location, lymphocyte count, frequency and duration of antibiotic utilization, and number of infection-related hospitalizations were recorded. Data was analyzed with Mann-Whitney U and Fisher’s Exact tests. Results: From a total of 131 patients with a diagnosis of head and neck lymphatic malformation, there were 45 pediatric patients with documented laboratory values included in the cohort. Lymphocytopenia was present in 24 (53%) patients. There were no differences in the number of patients requiring hospitalization for infection (8 vs 7, p=1.000), mean length of hospital stay (0.38 vs 0.48, p=0.891), or mean duration of antibiotic course (14 vs 15 days, p=0.833) between those with and without lymphocytopenia, respectively. Similarly, the subset of 5 patients on sirolimus treatment had no increased infection-related parameters when compared to the remainder of the cohort. Discussion: Lymphocytopenia was not associated with higher rates of infection requiring hospitalization or increased duration of antibiotic course in head and neck LM. Furthermore, patients receiving sirolimus did not incur higher rates of infection. Larger prospective studies are needed to follow disease course in patients with and without LM-associated lymphocytopenia.