Objective: Craniofacial bone is the most common involved site of Langerhans cell histiocytosis (LCH). The main purpose of this study is to clarify the relation between subsites of craniofacial bone and clinical presentation, treatment modalities and outcome of patients with LCH.
Material and Methods: 44 patients during 2001-2019 in a single medical center diagnosed with LCH with craniofacial bone involvement were retrospectively reviewed for demographics, clinical presentation, treatment and outcome. Chi-square and Fisher exact test were applied to evaluate the clinical presentation and outcome between different classification or involved site.
Results: The mean age of diagnosis was 11.8 years old with 68.2% of the patients contributed by patients under 10 years old. Mean duration prior to diagnosis was 7.02 weeks with the most common complaint of mass with or without tenderness (25 patients, 56.8%). The distribution of 4 subgroups was single system (SS) (26 cases, 59.1%), single system with multi-focal bone lesions (SMFB) group (9 cases, 20.5%), multi-system group without risk organ involvement (MS, RO-) (4 cases, 9.1%), multi-system group with risk organ involvement (MS,RO+) (5 cases, 11.4%) respectively. Temporal bone (66.7% vs 7.7%, p=0.001), occipital bone (44.4% vs 7.7%, p=0.035) and zygomatic bone (22.0% versus 0.0%, p=0.034) were more common in group with SMFB group comparing to SS group. The mean follow-up time was 81.34 months. 22 patients (91.6%) of SS group, 6 patients (75.0%) of SMFB group and 5 patients (62.5%) of multi-system group achieved complete remission during long-term follow up, with reactivation rate 15% (6 cases) and mortality rate 2.5 % (1 case). No difference of reactivation rate was noted in 4 groups. In terms of permanent consequences (PC), the most common one is diabetes insipidus in 9 of 16 PC patients. SMFB group (66.7% vs 15.4%, p=0.003), patients with occipital bone (77.8% versus 25.7%, p=0.007) and pituitary involvement (88.9% versus 22.9%, P=0.001) have higher incidence of PC. Single system was reported to be having lowest incidence of DI (7.7%, p=0.035). Reactivation rate was also higher in patients reported PC (33.3% versus 4.0%, p=0.021) or DI (62.5% versus 3.1%, p<0.001).
Conclusions: Except a lower mortality rate and higher PC incidence, this study reported similar characteristics of clinical manifestations and outcome in patients with LCH craniofacial involvement compared to previous studies. Moreover, involvement of some specific bone may indicate multifocal, multi-system disease or risk of PC development. Therefore, multidisciplinary evaluation and treatment according to risk stratification were vital for patients diagnosed of LCH with craniofacial involvement.