Behcet disease (BD) was described in 1937 by Hulusi Behçet from Istanbul, in patients with oral and genital ulcers, uveitis, and erythema nodosum. Even though it mainly presents with mucocutaneous features, other clinical manifestations were identified later and were added to the disease spectrum ^[1]. BD is a chronic auto-inflammatory condition that affects systemic blood vessels, nerves, musculo-skeletal system, and gastrointestinal system, apart from having recurrent mucocutaneous lesions. Non-erosive, asymmetric, and non-deforming arthritis of large and middle joints is the most common musculoskeletal manifestation. Arthritis is intermittent in nature and lasts for only weeks during the exacerbation period. It is seen in half of the patients, followed by enthesopathy, avascular necrosis, myalgia, and myositis. However, spinal column involvement is quite rare.

A 39 year old male, initially had posterior neck pain for 4 weeks and presented to the department of orthopedics. He did not have any neurological deficits or arthralgia in any other joints. On inspection, he had few pustules and pimple-like lesions on his neck and back. A blood test showed elevated erythrocyte sedimentation rate and C-reactive protein along with raised white blood cell and platelet count. On magnetic resonance imaging mild fluid with associated enhancing synovial thickening was noted involving the atlantoaxial joint (AAJ) on both sides with associated subtle altered signal intensities appearing STIR hyperintense and showed subtle enhancement of the dens, with no obvious bony erosion, suggesting inflammatory or infective etiology (Fig. 1). He was started on a trial of anti-tuberculosis drugs, considering cervical tuberculosis. He was then referred to the department of Dermatology with persistent neck pain as the lesions on his neck, back, and pustular lesions on his left forearm were increasing in number. He also developed oral ulcers. There was no history suggesting ocular complaints, genital lesions, neurological complaints, or trauma present. On examination, few grouped papules and pustules forming plaque of 2 × 2 cm are present on the left side of the neck and the inner aspect of the right forearm(Fig.2). Two 1 × 1 cm oral erosions with a pale base preset on a soft palate (Fig. 3). A provisional diagnosis of BD considered. Histopathology done from the left forearm lesion confirmed the diagnosis. Pathergy test was positive. On histopathology, the epidermis showed acanthosis with basal keratinocyte vacuolization, and the dermis has superficial and deep perivascular lymphohistiocytic infiltrate with few neutrophils and eosinophils, mild leukocytoclasia along with extravasated red blood cell confirming the diagnosis of BD (Fig. 4). He was started on T. Colchicine 0.5 mg with which his mucocutaneous lesions and posterior neck pain improved.

Behcet’s syndrome is a rare disorder with the triad of oral aphthae, genital ulcers, and recurrent iritis. This spectrum has been extended to include joint, skin, vascular, neurologic, and gastrointestinal disorders ^[2]. The etiology and pathogenesis of BD remain obscure. However, both genetic and environmental factors have been proposed to initiate an immune dysfunction that causes the development of the clinical manifestations of the disease ^[3]. Musculoskeletal involvement in BD is one of the most frequent findings among the clinical manifestations. Arthritis is seen in BD as non-erosive, peripheral oligo-arthritis in half of the patients ^[4]. The knees are most involved ^[5], and the spine is rarely involved ^[6]. To the best of our knowledge, there were two cases already diagnosed with BD, have reported on the progression of AAJ to AAJ dislocation [7,8]. Dislocation of AAJ is a fatal disturbance in the anatomy of the occipital-cervical structure. The stability of AAJ articulation can be lost in inflammatory, traumatic, idiopathic, and congenital etiologies. AAJ relationship can be evaluated on the lateral radiograph by assessing the measurement of the space between the anterior margin of the odontoid process and the posterior margin of the anterior arch of the atlas. It should not measure more than 3 mm in adults ^[9] and 5 mm in children ^[10]. Increase in this distance indicates atlantoaxial subluxation. Here, in our case, we report that BD can present with AAJ pain as an initial complaint preceding other systemic complaints or before diagnosing BD. We came across only one similar case in the literature, where a patient with BD presented with AAJ pain as the initial presenting complaint ^[11]. Diagnosing and treating Behcet’s syndrome associated with AAJ pain early can prevent joint dislocation and further associated fatal disturbances.

BD causing AAJ pain is quite rare. AAJ pain as the initial manifestation is reported only in one case. Even though it is rare, it is encouraged for clinicians to highly consider it as a differential diagnosis in patients with AAJ pain, especially with mucocutaneous lesions due to its fatal progression.

This report showed BD can also present unconventionally with spine involvement, causing AAJ pain as an initial manifestation rather than mucocutaneous or knee joint manifestations. Accurate identification and successful management of this case prevented further joint dislocation and complications. This report further added to the limited literature on the association of BD and AAJ involvement, and also provides guidance to the clinicians in evaluating and managing patients with atypical neck pain.