Tumeur mélanocytaire méningée primitive de grade intermédiaire : confrontation radio-pathologique

A rare case of multifocal craniospinal leptomeningeal melanocytoma: A case report and scoping review

Introduction

Leptomeningeal melanocytomas are rare tumours originating from neural crest derived melanocytes. They are usually solitary and presentation with multifocal meningeal melanocytoma is very rare and indicative of potentially more aggressive behaviour. This case report and scoping review sought to evaluate the presentation, and key radiological features that can help differentiate multifocal meningeal melanocytoma from other differentials and provide a discussion of the key management and prognostic points once these tumours are diagnosed.

Case presentation

A 26 year old male presented with neck pain radiating to both shoulders and subjective weakness in left shoulder movement. MRI demonstrated a large enhancing C2-C3 intradural-extramedullary lesion with further lesions at the T7/T8 level, left cerebellopontine angle and midline suprachiasmatic region. Whilst the imaging appearances were initially thought be indicative of a phacomatosis such as NF2-related schwannomatosis, surgical excision of the cervical tumour confirmed a melanocytic tumour of leptomeningeal origin, consistent with multifocal meningeal melanocytoma. Patient made a good post-operative recovery and remains under half yearly radiological surveillance, with repeat MRI 6 months after surgery demonstrating subtle growth of the untreated intracranial and spinal lesions.

Literature review and conclusions

This is the first description, to our knowledge, of a multifocal meningeal melanocytoma associated with both cerebellopontine angle and suprasellar lesions. This case and included scoping review highlight the need to consider this rare diagnosis whenever multifocal craniospinal lesions are encountered, and the need to consider aggressive management through surgical resection and adjuvant craniospinal radiotherapy once these tumours are diagnosed.

Orbital meningeal melanocytoma: Histological, immunohistochemical and molecular characterization of a case and review of the literature

AIMS

We provide morphological, immunohistochemical and molecular characterization of the 3rd "intermediate-grade" orbital meningeal melanocytoma, testing for the first time Vysis Melanoma FISH Probe Kit. We reviewed the literature in order to discuss the main differential diagnoses and to provide a better molecular description of these unusual tumors of difficult diagnosis and controversial management.

METHODS

Histochemical stains (Haematoxylin and Eosin, Perls, reticulin), immunohistochemistry (HMB45, p16, Melan-A, S100, EMA, Ki67, CD68), polymerase chain reaction amplification and sequence analysis (BRAF, exon 15; NRAS exons 2 and 3; c-KIT, exons 11, 13, 17, 18; GNAQ, exons 4 and 5; GNA11, exons 4 and 5) and fluorescent in situ hybridization (RREB1, 6p25; MYB, 6q23; CCND1, 11q13; CEP 6, 6p11.1-q11.1) were performed on paraffin-embedded, formalin-fixed material.

RESULTS

Histological diagnosis of "intermediate-grade" melanocytoma was supported by zonal necrosis and increased Ki67-index (12%). Immunophenotype: HMB45+(strong, >75%), Melan-A+(strong, >75%), p16+(∼20%), S100 -/+ (<5%), EMA -/+ (<5%), CD68 - (positive histiocytes). No gene mutations nor copy-number alterations were identified. The patient was asymptomatic and disease-free 3 years after total surgical excision.

CONCLUSIONS

Adequate sampling and accurate immunohistochemical characterization are important for a correct diagnosis. Molecular analysis could provide important additional information (especially for "intermediate-grade" tumors), but further data are needed.

Primary scattered multifocal melanocytomas in spinal canal mimicking neurofibromatosis

BACKGROUND CONTEXT

Meningeal melanocytoma is an extremely rare pigmented tumor derived from leptomeningeal melanocytes. By and large, it is considered to be a well-differentiated and slow-growing benign lesion. Generally, meningeal melanocytomas are solitary lesions, and the occurrence of the primary multifocal form in the central nervous system is exceedingly rare; it has been previously reported in only six cases.

PURPOSE

The present report illustrates a 41-year-old woman with primary multifocal meningeal melanocytoma in the spinal canal. Contrary to earlier reports, the tumors presented with a scattered appearance mimicking neurofibromatosis.

STUDY DESIGN

This study is a case report and review of literature.

METHODS

On admission, the cerebral magnetic resonance images of the patient were normal, whereas the spinal magnetic resonance images showed scattered multifocal nodules mimicking neurofibromatosis. Surgical resection of the responsible lesions was scheduled. In addition to this case presentation, relevant previous reports were reviewed, and the challenging diagnosis, management, and prognosis of meningeal melanocytoma are discussed.

RESULTS

Gross total resection of the two largest lesions was achieved, and histopathological examinations confirmed the diagnosis. Despite the benign histopathological findings, the patient had an aggressive clinical course. On follow-up at 18 months after surgery, she succumbed to the disease.

CONCLUSION

Clinicians should be alert to a potential aggressive clinical course of meningeal melanocytoma, despite its benign histopathological nature. Of particular note is multifocality and diffuse leptomeningeal hyperpigmentation, which may suggest a poor prognosis. A combined treatment including surgical resection and adjuvant radiotherapy should be considered, and long-term close follow-up is necessary.

Intermediate-grade meningeal melanocytoma associated with nevus of Ota: a case report and review of the literature

Meningeal melanocytomas are rare melanin-producing tumors that are often found to be benign. However, a small subset of these tumors can present as intermediate-grade melanocytomas (IGMs) that have histopathological features that are between those of benign melanocytomas and malignant melanomas. IGMs have the potential to recur and metastasize or progress to a more histologically high grade melanoma. Melanocytomas appear to differ from primary and metastatic melanoma by their prolonged clinical course and they appear to have different driver mutations (i.e. mutation of GNAQ gene). The association of a meningeal melanocytoma with nevus of Ota is extremely rare. To our knowledge, there have been only 10 reported cases of synchronous occurrence and only one of the cases involved an IGM. We report the second case of intermediate-grade meningeal melanocytoma that is associated with congenital nevus of Ota. Histopathological work-up confirmed the intermediate grade of the lesion and a driver GNAQ mutation was identified consistent with previous reports.

[Pituitary melanocytoma mimicking an adenoma]

A 62-year-old woman was referred for a pituitary tumour diagnosed because of a chronic asthenia and visual disorders. Cerebral MRI showed a pituitary tumour compressing the optic chiasm and enhanced after gadolinium injection. Biological findings showed panhypopituitarism and hyperprolactinemia. The diagnostic of pituitary macro-adenoma was performed and the patient was treated with hormone replacement therapy and dopaminergic agonist. Six months later, she presented visual disorders worsening leading to surgical excision. The diagnosis of pituitary melanocytoma was performed after anatomo-clinical confrontation. Post-operative radiation was done.