Uncorrect diagnosis of tubercolar spondylodiscitis in aggressive and bone destructive metastasis of melanoma: A case report and literature review

Abstract

Differential diagnosis of destructive osteolytic spinal lesions can be a diagnostic challenge. In this study, we described a rare case of spinal metastases from primary desmoplastic melanoma which had incorrectly been diagnosed and treated as tuberculous spondylodiscitis. An 82-year-old male patient with ongoing low back pain and a history of lumbar localized Pott's performed a lumbar spine MRI that showed osteolytic lesion with first hypothesis of spondylodiscitis L2-L3. The patient was hospitalized and cause of worsening of the lumbar pain underwent a following series of non-diagnostic CT-guided and open lumbar biopsy at L2-L3 with unsuccessful antibiotic-antitubercular therapy. A new MRI revealed a worsening of previous lesions, extension of the osteolytic lesion at the level of L1-L2 and L3-L4 with neurological impairment. The diagnosis of metastatic melanoma was obtained with surgical decompression and open posterior biopsy procedure. The case described is pathognomonic of the difficulty in detecting the correct diagnosis in front of similar clinical and radiological manifestations. The presence of a previous Pott's disease in the same involved vertebral site was of crucial importance in deflecting the correct diagnostic classification of the pathology, which was possible to ascertain only following an extensive biopsy sampling in the last surgery performed.

Keywords: Malignant Melanoma; Osteolytic spinal lesion; Spinal metastases; Tubercolar spondylodiscitis.

Figure 1.

MRI scan of the lumbar spine performed at a different hospital when the diagnosis of osteolytic lesion at L2-L3 level was first established. After the MRI, a CT-guided biopsy was performed which was non diagnostic.

Figure 2.

First MRI scan of the lumbar spine performed after admission at our hospital. The MRI scan confirms the presence of an osteolytic lesion at L2-L3 level with extension to the posterior elements and pre-vertebral tissues. A repeat CT guided biopsy was performed but again was not conclusive.

Figure 3.

Repeat MRI scan of the lumbar spine after 8 weeks of anti-tuberculous therapy. Patient had worsening pain and bilateral proximal weakness in the lower limbs. There is also further spread to the posterior elements and ileo-psoas muscles. The patient underwent an extended open biopsy which confirmed the final diagnosis of metastatic desmoids melanoma.