Cauda equina aspergilloma in an immunocompetent individual: A case report.

The authors report an unusual case involving a 70 year old man who came with severe low back pain radiating to both legs, magnetic resonance imaging (MRI) lumbosacral spine reveled nodular spinal intradural lesions involving Cauda equina for which he was operated. Histopathological examination of the operative specimen revealed large granulomas with multinucleate giant cells lining zones of necrosis and within the granuloma numerous septate branching hyphae of Apsergillus spp highlighted by Gomori methenamine silver stains which was suggestive of aspergillosis. There is no reported case of Cauda equina aspergilloma in an apparently immunocompetent person before this.

INTRODUCTION

Aspergillus may reach the central nervous system by three different routes.[1] The first one is by hematogenous dissemination from a remote extracranial site, usually the lung. The second one is by the extension from a contiguous cranial focus. This focus is most often the nasal cavity and the paranasal sinuses from which the fungus may reach the intracranial cavity by direct propagation and ultimately spread to involve the spinal cord. The third possibility is by direct introduction into patients who develop intracranial aspergillosis after neurosurgical procedures. There are various clinical forms of this infection: Aseptic[12] and persistent meningitis, mycotic aneurysms,[2] ischemic, and hemorrhagic infarcts and the tumor-like form or aspergilloma.

CASE REPORT

A 70-year-old gentle man, fruit vendor walked with difficulty into our outpatient department. He described shooting pain from low back into both legs and buttocks since 3 months. He has hypertension and is taking antihypertensives for 25 years. Neurological examination revealed saddle region parasthesia. Bladder and bowel were intact and there were no deficits in legs.

Magnetic resonance imaging (MRI) scan of spine and brain [Figures 1 and 2] showed enhancing T1 intermediate and T2 hypointense three soft tissue nodulations along the cauda equina at L2, L4, and L5-S2 filling the thecal sac in the lumbosacral region. At S2 level the soft tissue mass was scalloping the canalicular cortex. There was no intracranial abnormality. Considering age of patient serum electrophoresis was done which was not suggestive of myeloma. Prostate specific antigen was normal. X-ray chest was normal, ultrasound scan of the abdomen and pelvic did not show any abnormality or enlarged lymph nodes. Enzyme-linked immunosorbent assay (ELISA) for human immunodeficiency virus (HIV) I and II was nonreactive. Complete hemogram, blood sugar, and Hb1Ac were in normal range.

Figure 1

Magnetic resonance imaging (MRI) scan of lumbosacral spine showing enhancing T1 intermediate three soft tissue nodulations along the cauda equina at L2, L4, and L5-S2 filling the thecal sac

Figure 2

MRI scan of lumbosacral spine showing T2 hypointense three soft tissue nodulations along the cauda equina at L2, L4, and L5-S2 filling the thecal sac. At S2 level the soft tissue mass was scalloping the canalicular cortex

Patient was operated in prone position, under general anesthesia. L5 to S2 laminectomy and total excision of lower lesion was done. The lesion was involving the filum terminale and firmly stuck to the nerve roots and both S3 roots had to be sacrificed. The higher nodular lesions at L2 and L4 were left untouched. Operative specimen was sent for histopathological examination [Figure 3] which showed large granuloma with multinucleate giant cells lining zones of necrosis (A). Within the granuloma are numerous septate branching hyphae of Apsergillus spp highlighted by Gomori methenamine silver stains (B). Diagnosis of aspergiloma was established.

Figure 3

Histopathological examination of the operative specimen shows large granuloma with multinucleate giant cells lining zones of necrosis (a). Within the granuloma are numerous septate branching hyphae of Apsergillus spp highlighted by Gomori methenamine silver stains (b)

Patient received 4 weeks course of intravenous amphotericin B 35 mg daily and oral itraconazole 200 mg twice a day. Patient tolerated antifungal course well.

DISCUSSION

Aspergillosis of the central nervous system is an uncommon infection, mainly occurring in immunocompromised patients with an incidence of 18.3%.[2] It may be present in several forms, meningitis, mycotic aneurysms, infarcts, and the tumoral form (aspergiloma). Aspergiloma is even rarer in patients who are apparently immunocompetent.

Diagnosis of aspergiloma in immunocompetent patients remains difficult because medical staff rarely suspects this condition. Although such patients have much better prognosis than for immunocompromised patients, the diagnosis is frequently missed or delayed.[2]

In our patient there were no predisposing factors and no fungus isolated in bronchial secretions. The infection was probably via hematogenous route, and MRI spine was not different from any other intradural spinal tumor. Considering the age of patient and multiple lesions a probable diagnosis of metastasis was expected. The histopathological examination of the operative specimen was suggestive of aspergiloma. There is no case of spinal cord aspergiloma in an apparently immunocompetent in the literature.