An unusual presentation of eosinophilic granuloma in an adult: a case report

Journal of Orthopaedic Surgery, Apr 2006 by Garg, B, Sharma, V, Eachempati, K K, Malhotra, R, Bhan, S

ABSTRACT

Eosinophilic granuloma is the most common and benign form of a rare proliferative disorder-Langerhans' cell histiocytosis. Spinal involvement is rare and only 15 adult cases have been reported. We present an unusual variant of eosinophilic granuloma in a 25-year-old woman with radiological evidence of vertebra plana. Plain radiography, magnetic resonance imaging, bone scan, and blood tests were carried out, and a specimen was taken from L4 using computed tomography-guided biopsy. Gram staining, acid fast bacillus smear, bacterial and fungal cultures were negative. Histological examination of the biopsy showed features of eosinophilic granuloma with aggregates of Langerhans histiocytes. The patient was treated with low-grade radiotherapy at 150 cGy per day for 7 days. She was asymptomatic at one-year follow-up although the radiological picture was unchanged.

Key words: eosinophilic granuloma; langerhans cells; spine

INTRODUCTION

Langerhans-cell histiocytosis of the bone represents a spectrum of diseases that are defined histologically by a common proliferative agent-Langerhans cell or histiocyte. The diseases include eosinophilic granuloma, Hand-Schueller-Christian syndrome, and Letterer-Siwe disease.1 Eosinophilic granuloma is the most common and benign form; the others constitute the acute and sub-acute forms of histiocytosis X.2 Spinal involvement of eosinophilic granuloma is rare and only 15 adult cases have been reported.2 The classic presentation of eosinophilic granuloma in children involves the thoracic spine that appears as 'flattened' vertebrae or vertebrae plana. Nonetheless, in adults relatively small areas of the vertebral body are affected with no associated vertebral collapse. None of the 15 adult cases reported had radiological evidence of vertebra plana.2 We present an unusual variant of eosinophilic granuloma in a 25-year-old woman with radiological evidence of vertebra plana.

CASE REPORT

In May 2003, a 25-year-old woman presented to the All India Institute of Medical Sciences in New Delhi, India. The patient had an 8-week history of pain in the lumbosacral region. She was diagnosed with Pott's disease (spinal tuberculosis) and was prescribed antitubercular chemotherapy. After 6 weeks, the pain persisted and was aggravated by bending anteriorly. There were no motor or sensory deficits in the lower limbs, no paraesthesia or tingling, and no bladder or bowel problems. The patient had no history of fever, weight loss, or constitutional symptoms. Plain radiographs of the lumbosacral spine showed a typical 'coin-edge' appearance of vertebra plana at the L4 level with intact intervertebral discs above and below (Fig. 1). Haemogram, erythrocyte sedimentation rate, and serum chemistry including calcium, phosphate, and alkaline phosphatase levels were normal. Magnetic resonance imaging revealed complete collapse of L4, marrow signal changes (hypointense on T1-weighted and slightly hyperintense on T2-weighted/STIR [short T1 inversion recovery] images), and indistinct superior and inferior endplates (Fig. 2). The adjoining discs were normal in height and signal intensity. An anterior epidural collection was slightly hyperintense on T1-and T2-weighted images and compressed the thecal sac. Pre- and para-vertebral soft-tissue shadow was also seen. Bone scan revealed increased radio-trace uptake over L4 vertebra.

Computed tomography-guided biopsy was performed on the L4 vertebra. Gram staining, acid fast bacillus smear, bacterial and fungal cultures of the specimen were negative. Histological examination revealed features of eosinophilic granuloma with aggregates of Langerhans' histiocytes (Fig. 3).

The patient was treated with low-grade radiotherapy at 150 cGy per day for 7 days. She was asymptomatic one-year later although the radiological picture was unchanged.

DISCUSSION

Eosinophilic granuloma constitutes less than 1% of all bone tumours,3 and the vertebral body involves in around 7% to 15% of cases.4 Approximately 80% of patients present before the age of 10 years, making this a disease of childhood.2

The spinal lesions may be asymptomatic on routine X-ray films, and most patients present with sudden or gradual onset of pain. In younger children, most of the body can be affected; hence, the classic waferlike collapse is often described. In older children, relatively smaller areas are affected, and segmentai collapse tends to result.5

The level of spinal involvement varies at different ages. In children, the thoracic spine (54%) is the most common location, followed by the lumbar (35%) and cervical spine (11%). In adults, 47% of reported cases involve the cervical spine, 33% the thoracic spine, and 20% the lumbar spine.2 In another study of Langerhans' cell histiocytosis (the whole spectrum) in 541 patients older than 21 years, the lesions were almost exclusively thoracic (6 of 7).1

The differential diagnoses include aneurysmal bone cyst, osteomyelitis, Ewing's sarcoma, osteoblastoma, Gaucher's disease, acute leukaemia, and metastatic tumour.2 The diagnosis of eosinophilic granuloma is based on histological and histochemical identification. Electron microscopy may show Birbeck's granules in the cytoplasm.