The authors have declared that no competing interests exist.
Melanocytoma is a rare benign lesion arising from leptomeningeal melanocytes. Meningeal melanocytomas are commonly seen in the thoracic region of the spinal canal and may also arise in the cervical or lumbar region, most often located in the intradural extramedullary compartment
Melanocytoma is a rare benign lesion arising from leptomeningeal melanocytes. It was first described by Limas and Tio in 1972. Melanocytoma usually has an intracranial localization but may occur in the spine too. Meningeal melanocytomas are commonly seen in the thoracic region of the spinal canal and may also arise in the cervical or lumbar region, most often located in the intradural extramedullary compartment
A 74-year-old woman presented complaining a several-month history of increasing thoracic back pain and left leg pain. Neurological examination demonstrated a spastic paraparetic gait and hyperreflexia of the lower limbs. Spinal magnetic resonance imaging revealed an intramedullary mass extending from T7 to T11 measuring 22 x 12 x 15 mm, slightly hyperintense on T1weighted images and hypointense on T2 weighted sequences and showed mild and heterogeneous enhancement after injection of gadolinium (
The patient had no bowel or bladder dysfunction but preexisting left hemiparesis worsened immediately after surgery. She underwent rehabilitation, and at 2 months post surgery had regained full strength. Histological examination revealed neoplasia mainly consisting of spindle-shaped monomorphic cells with clearly visible nucleoli and melanin-rich cytoplasm. It exhibits low mitotic activity, and stains positively with HMB-45 and S-100, indicating cells of melanocytic origin. The histological diagnosis was consistent with a melanocytoma.
A computer-aided search of MEDLINE was conducted from 1990 to 2012. The search was performed using keywords as “melanocytoma”, “intramedullary spinal cord tumor” and was limited to human studies.
Only 21 cases have been described in literature to date, we summarize in the
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
---|---|---|---|---|---|---|---|---|
Barth |
49 | F | T10-T12 | 2 subtotal | 4 years | Yes | Yes | No |
Glick |
69 | M | C1-C2 | Total | 5 years | No | No | No |
Glick |
39 | F | T8-T9 | Subtotal | 1 year | No | No | Yes |
|
||||||||
Delhaye |
38 | F | T6-T9 | 2 subtotal | 4 years | Yes | Yes | No |
Turhan |
19 | F | T8 | Total | 3 years | No | No | No |
Van Paesschen |
51 | M | C1-C2 | Total | - | No | No | No |
Horn et al. 2008 | 37 | F | C1-3 | Total | 3 years | Yes | No | No |
Caruso |
62 | M | T11 | Total | 2 years | No | No | No |
Karikari IO et al. 2009 | 32 | F | T10 | Total | 3 months | No | No | No |
Eskandari R, et al 2010 |
45 | M | T11 | Subtotal | 3 years | No | yes | Yes |
M. Muthappan et al 2011 |
61 | F | C3-4 | Total | 3 years | No | No | No |
Table 1 provides a summary of reports involving intramedullary melanocytomas
As we observed in the literature this tumor is most commonly found in women with an average age of 45,9 years (range, 19–79 years). The biological behavior is most commonly benign, although these tumours are slow growing, they have a propensity to recur, metastasize via the cerebrospinal fluid, and undergo malignant transformation. In the literature 12 cases out of 21 have been radically removed and never relapsed (follow up 3,5 years).
The goal of treatment should be complete/gross total resection with preservation of neurological function. Radiotherapy is generally provided when resection is incomplete
Melanocytomas are neural crest-derived cells which are normally found within the basal layer of the epidermis and the leptomeninges that cover the base of brain and the brain stem. Moreover, the highest concentration of melanocytes is seen ventrolateral to the medulla oblongata and upper cervical levels of spinal leptomeniges. The term ‘meningeal melanocytoma’ was first proposed by Limas and Tio in 1972 based on ultrastructural features to differentiate these benign pigmented tumors from those originating from meningothelial fibroblasts. Since then, less than 100 cases have been reported in the literature. Macroscopically, melanocytoma can be dark-to-tan (
Typical MRI show an intramedullary lesion that appears isointense on T1-weighted sequences, hypointense on T2 weighted sequences, and enhances homogenously with gadolinium. These signal features are inconsistent due to the variable degree of tumour melanisation, which affects the signal characteristics on MRI. Hence, meningeal melanocytoma should be included in the differential diagnosis of lesions as ependymoma, meningioma and intramedullary astrocytoma
Although these tumours are slow growing, they have a propensity to recur, 7 out of 21 cases described in the literature and to metastasize, 4 cases found in the literature, via the cerebrospinal fluid, and undergo malignant transformation. Rades and Schild reported that some patients with a meningeal melanocytoma might have recurrence even after complete tumor resection
Tumour recurrence has been reported as early as three months after surgical resection; hence, it is crucial that these patients are followed up regularly with serial MRI and clinical assessment to identify early recurrence. In the event of local recurrence, operative resection is a reasonable treatment option, although it may be associated with significant morbidity; the alternative is radiation treatment. Additional information is required regarding the long term outcome of melanocytoma after surgical resection and radiotherapy, to enable improved treatment strategies.
Intramedullary melanocytoma is extremely rare. The majority of these leptomeningeal tumors are extramedullary, and only few cases of intramedullary tumors have been reported. As with most rare tumors, only case reports are available for reference; thus, no gold standard exists for the definitive treatment and follow-up of patients with these tumors. We favor radical tumor resection when possible and close follow up monitoring since these tumors can recur. Radiation therapy should be reserved for those cases in which complete resection is not possible or in which there is recurrence.