Discussion
Langerhans cell histiocytosis, formerly known as histiocytosis X, is a term used to describe a group of clinico-pathological conditions marked by a monoclonal proliferation of histiocyte-like cells followed by varying numbers of eosinophils, lymphocytes, plasma cells, and multinucleate giant cells on histological examination.5 The histiocytes present here is recognised as Langerhans cells. Langerhans cells are dendritic mononuclear cells which are generally found in the epidermis, mucosa, lymph nodes, and bone marrow. They generally present antigens to T-lymphocytes; however literature review of LCH indicates that Langerhans cells proliferate monoclonally, resulting in the destruction of hard and soft tissues.6 Despite significant progress in medical fields, the pathophysiology of LCH remains unclear; suggested mechanisms are the product of either an abnormal autoimmune response or a neoplastic process.4
LCH can affect people of wide age range, but it is more common in children under the age of 15 years, with a peak occurrence at 2–4 years and a male predilection that is twice as high as that of females.2 The present case was reported in a five-year-old male child. The jaws are involved twice as commonly as the oral soft tissues. The mandible is three times more frequently affected than the maxilla with a higher predisposition for the posterior regions of the jaws than the anterior regions.7 These findings are similar to the present case where mandibular posterior regions were affected more. In about 5%-75% of patients, oral manifestations are the first signs and symptoms and sometimes the only symptom of LCH, thus, prompting the patient to seek treatment from a dentist.8 Eden P et al., reported in a case series (n=13) that seven of the cases showed intra-osseous lesion in the posterior region of the jaw and oral mucosal involvement (tongue, buccal mucosa and gingiva).9 Sore throat, halitosis, gingivitis, gingival hypertrophy, unpleasant taste, tooth mobility with alveolar expansion, jaw pain, facial swelling, mental nerve anaesthesia, and inability of extracted tooth sockets to heal are some of the oral symptoms. The loss of supporting alveolar bone may be mistaken for advanced periodontitis.8 In the present case, palatal ulcer, tooth mobility, pain, and bone loss were the features in consideration.
According to Krooks et al., the involvement of nails is uncommon, but can be seen as subungual pustules, hemorrhage, purpuric striae, purulent discharge, longitudinal grooving, onycholysis, paronychia, and pitting.4 In the present case as well, changes in the nails were evident. LCH lacks the pathognomonic clinical or radiographic features, thus, a definite diagnosis is based on a histologic and immune-histochemical examination, where CD1a, Langerin (CD207), and S-100 protein positivity is common.10 S-100 is a calcium binding protein present in the nucleus and cytoplasm of glial and schwann cells, melanocytes, chondrocytes, adipocytes and myoepithelial cells and is positive for all tumors derived from these cells. CD1a is expressed on Langerhans precursors, Langerhans cells and thymic cortical T cells, whereas Langerin is a type II transmembrane cell surface receptor produced by Langerhans cells which helps in differentiating Langerhans cell histiocytosis from other non-Langerhans cell histiocytic proliferations. As in our case immunostaining was positive for CD1a, Langerin, and S-100, it helped in confirming the diagnosis of LCH.
The dentists are usually the first clinicians to examine the child’s oral cavity, hence, awareness regarding the varied manifestations of this rare condition is important for early diagnosis and appropriate referral of the patient. Also, multidisciplinary approach is necessary for the overall management and well-being of the child. Since, the lesions present in LCH may be confounded with a malignant process, histological and immune-histochemical tests play a vital role in confirming the diagnosis.3
Conclusion
Langerhans cell histiocytosis is a disease with a wide range of clinical symptoms. LCH, being a rare condition, is at a high risk of being misdiagnosed or underdiagnosed. A thorough history, clinical examination, appropriate investigations and a sound knowledge of the condition helps to make a correct diagnosis at an early stage, thus reducing the morbidity and mortality associated with this pathology. An interdisciplinary approach is also imperative for the success of the management of the condition.