Study Design: This case report describes infection in a lumbar disc in a healthy young man with an organism of low pathogenicity. The patient was taking a prolonged course of antibiotics at the time the infection occurred.

Objective: To describe this unique case of infective spondylodiscitis.

Summary of Background Data: To the authors' knowledge, spinal infection with Enterobacter agglomerans has never been reported. This organism is a transient gut colonizer, and may have established itself secondary to the patient's prolonged ingestion of tetracycline for acne.

Methods: This 22-year-old farmer had spontaneous lumbar back pain. Radiologic investigations showed an abnormality in the L4-L5 disc region, and together with other investigations, were suggestive of infection. The diagnosis was confirmed by surgical aspiration.

Results: Antibiotic therapy was administered, and the patient made a complete recovery. Follow-up radiographs showed a complete loss of the L4-L5 disc space with only minimal bone destruction.

Conclusion: A unique cause of infective lumbar discitis is presented. Several features of this case are unusual. The magnetic resonance findings were not readily diagnostic. The cultured organism is usually nonpathogenic. The infection may have been secondary to prolonged tetracycline therapy.

Extraspinal tendon and ligament calcification associated with long-term therapy with etretinate
J.J. DI GIOVANNA, ET AL

Isotretinoin, a synthetic retinoid that has been prescribed for over 500,000 patients with cystic acne, has been associated with both spinal hyperostoses and a disorder similar to diffuse idiopathic skeletal hyperostosis. We describe a syndrome of tendon and ligament calcification, primarily in extraspinal locations, that we have observed after long-term therapy for psoriasis and disorders of keratinisation with etretinate, another synthetic retinoid. Of 38 patients who had received etretinate (average dose, 0.8 mg per kilogram of body weight per day; average duration, 60 months), 32 (84%) had radiographic evidence of extraspinal tendon and ligament calcification. The most common sites of involvement were the ankles (29 patients-75%), pelvis (20patients-53%), and knees (16 patients-42%); spine involvement was uncommon in this group of etretinate-treated patients. Involvement tended to be bilateral and multifocal. Fifteen (47%) of the 32 affected patients had no bone or joint symptoms at the sites of radiographic abnormality. Thus, tendon and ligament calcification can occur without vertebral involvement as well as in association with it (for example, as part of the spectrum of diffuse idiopathic skeletal hyperostosis). We have identified extraspinal tendon and ligament calcification as a toxic effect that is commonly associated with long-term etretinate therapy.

Spinal cord compression/etretinate/vitamin a/acne/psoriasis
P. TFELT-HANSEN, ET AL

The vitamin a analogues etretinate and isotretinoin have been used for more than 10 years by dermatologists in the treatment of severe cystic acne and therapy resistant psoriasis and hyperkeratotic disorders. Among several long- term side-effects spinal hyperostosis and calcification of spinal ligaments havecaused special concern because of the potential for compression of the spinal cord. Radiographic monitoring of the axial skeleton before and during treatmentwith retinoids has been recommended. We report a case of subacute compression of the thoracic spinal cord probably caused by etretinate, where radiographic monitoring proved inadequate. A 35 year old man with hidrotic ectodermal dysplasia was treated for nine years with etretinate in a mean daily dose of 50mg (range, 25-100mg) because of severenail and skin problems with paronychia and ulceration. In june 1988, he had painful paraesthesia in the left leg and was seen by a neurologist. Discrete signs of sensory neuropathy were confirmed by neuro-physicological examination. In july the patient had weakness of the legs, and from the beginning of august he had numbness in the lower part of the body and legs. Although 99mtc scintigraphy and radiography of the thoraco-lumbar spine showed spondylosis unchanged from 1986, etretinate was discontinued. At the end of august neurological examination revealed hypalgesia distal to the umbilicus, absence ofvibration sense in the lower extremities, and a partial spastic paraplegia (muscle strength was decreased to 50% of normal for hip flexion). Patellar reflexes were hyperactive and a babinski sign was elicited in the left foot. Sphincter function was unaffected. Computed tomography with contrast demonstrated a severe encroachment on the spinal cord due to exostoses from the facet joints at t8-9. Similar but less extensive exostoses, not causing compression of the spinal cord, were seen from the facet joints at t7-8, t9-10 and t10-11. Myelography showed partial block of contrast at the lower border oft8. Extensive hyperostoses from the laminae and the facet joints compressing the cord at several levels (t7-11) were removed at laminectomy. After five months of rehabilitation, the patient can walk with a stick. Muscle strength in the lower extremities is normal but he has slight spasticity and hyperactive reflexes. Pain perception is normal and he can feel vibration on the toes. Thus, in our patient, despite normal radiographs of the thoracic spine and 99mtcscintigraphy, the spinal cord was severely compressed. A correct diagnosis was not made until computed tomography with subarachnoid contrast was done.