The GNAQ in the haystack: intramedullary meningeal melanocytoma of intermediate grade at T9–10 in a 58-year-old woman

Abstract

M eningeal melanocytomas are extremely rare tumors originating from leptomeningeal melanocytes. The first reported description, in the early 1970s, was by Limas and Tio.10 Although little is known about this tumor entity as only a few case reports have been published over the past few decades, the tumors mostly occur along the spine and the posterior fossa with a peak incidence around the 5th decade and a slight female predominance. 3,11 According to the classification suggested by Brat et al., 2 melanocytic neoplasms are categorized histologically as melanocytomas, melanocytomas of intermediate grade, or melanomas exhibiting typical malignant features such as necrosis and high mitotic activity. Recent in-depth molecular characterization of melanocytomas revealed distinct mutational and chromosomal fingerprints separating melanocytomas from other melanotic tumors such as melanoma metastases or melanotic schwannomas. 6Treatment aims at the complete surgical removal of the tumor and postoperative adjuvant radiotherapy. case reportA 58-year-old woman presented with a history of progressive ataxia, progressive urinary and bowel incontinence, and weight loss of 6 kg over a period of 6-8 weeks. Neurological examination revealed a paraparesis of the lower extremities (M0/5 muscle strength grade of the right leg; M1-2/5, left leg) with paresthesia and hypesthesia starting from the T-10 dermatome downward.Her medical history included breast cancer diagnosed in 2008, which was treated with a lumpectomy, adjuvant chemotherapy (6 cycles of Taxotere, Adriamycin, and cyclophosphamide), and postoperative whole breast radiotherapy (including supraclavicular lymph nodes) with a total dose of 50.4 Gy and followed by a 16-Gy boost to the tumor bed.Upon admission, MRI of the spine revealed a 3.7-cm isodense/slightly hyperintense intramedullary lesion at T9-10. After administration of gadolinium, the lesion appeared hyperintense on T1-weighted images (Fig. 1A). T2-weighted images showed a myelopathy signal from T-7 to T-12. The differential diagnosis included ependymoma, astrocytoma, and intraspinal metastasis.The patient thus underwent a laminectomy at the T9-10 levels and a complete microsurgical resection of the intramedullary tumor under continuous neuromonitoring. The lesion was grayish-red and heavily vascularized with a macroscopic appearance that closely resembled an epen- Meningeal melanocytomas are rare tumors. They are derived from leptomeningeal melanocytes and predominantly occur along the spine and the posterior fossa. Here, the authors report a case of intramedullary melanocytoma of intermediate grade in a 58-year-old female patient who was initially misdiagnosed with malignant melanoma until mutational analyses of a panel of genes associated with melanotic tumors led to reclassification.

Primary melanotic tumors of the nervous system: a consecutive case series

“…Identification of GNAQ G209L facilitated diagnosis in this case. The mutation appears to be pathognomonic for melanocytoma while BRAF-and NRAS-mutations are absent [8,9]. Psammomatous melanotic schwannoma frequently occurs in the context of Carney complex, which needs to be ruled out in such patients [10].…”

“…Identification of GNAQ G209L facilitated diagnosis in this case. The mutation appears to be pathognomonic for melanocytoma while BRAF‐ and NRAS‐mutations are absent [8,9].…”

Multifocal primary melanoma of the cervical spinal cord successfully treated by tumorectomy: a case report

“…Nevertheless, distinguishing between a malignant melanoma, a welldifferentiated melanocytoma, and an intermediate-grade melanocytic lesion [3] remains a diagnostic challenge. Hoffmann et al [7] recently suggested that molecular analysis was the best method for distinguishing between melanocytoma and malignant melanoma.…”

Primary Intramedullary Meningeal Melanocytoma in Cervical Spine: A Case Report and Literature Review

“…However, many case reports have recommended its complete resection. Melanocytoma is generally considered a benign disease but has the potential to recur and become malignant 7,15,16 .…”