Neurocutaneous melanocytosis‐associated malignant melanoma presenting with peritoneal seeding

Abstract Neurocutaneous melanocytosis (NCM) is a rare disease characterized by excessive proliferation and deposition of melanocytes in the leptomeninges and brain parenchyma, occurring in children with large congenital melanocytic nevi (LCMN). Manifestations of NCM range from asymptomatic CNS melanin deposition to cranial neuropathies, seizures, and hydrocephalus. Patients with NCM are at risk for malignant melanoma. We conducted a retrospective, single-institution study of patients with LCMN evaluated at Memorial Sloan Kettering Cancer Center from June 2000 to January 2020. Of 55 patients studied, 15 had no radiographic NCM, and 40 had radiographic NCM at initial evaluation. MRI findings included: focal melanocytosis (33), diffuse leptomeningeal disease (4), solid melanoma (3). Malformations were identified in 13, including arachnoid cyst (4), congenital hydrocephalus (4), Dandy-Walker malformation (3), and tethered cord (1). Twenty-one patients completed imaging once and were followed clinically. Seventeen with serial imaging (10 with focal melanocytosis, 7 with normal MRI) remained stable over a median 24-month follow up (range: 1–124). Six had suspected radiographic progression of NCM without melanoma. Malignant melanoma developed in 11 patients, 5 with focal melanocytosis on initial imaging. Median time from focal melanocytosis identification to melanoma diagnosis was 80 months (range: 18–200). Median age at melanoma diagnosis was 9.9 years (range: 1.1–25.3). Median survival from melanoma diagnosis was 9.1 months (range: 1–60.4). Focal NCM on neuroaxis imaging does not predict time to transformation to malignant melanoma. Serial imaging is not indicated in absence of disease-modifying treatment. Clinical follow up of at-risk individuals is essential in early identification of complications.

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NCOG-60. MALIGNANT MELANOMA IN NEUROCUTANEOUS MELANOCYTOSIS: A RETROSPECTIVE CASE SERIES (2000-2020)

Neuro-Oncology ◽

10.1093/neuonc/noaa215.598 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii142-ii143

Author(s):

Kevin Elmore ◽

Ugur Sener ◽

Elsie Ennin ◽

Stephanie Suser ◽

Ashfaq Marghoob ◽

...

Keyword(s):

Radiation Therapy ◽

Malignant Melanoma ◽

Cutaneous Melanoma ◽

Case Series ◽

Cancer Center ◽

Leptomeningeal Disease ◽

Molecular Testing ◽

Braf Mutations ◽

Melanoma Diagnosis ◽

Neurocutaneous Melanocytosis

Abstract Neurocutaneous melanocytosis (NCM) is a rare neurocutaneous syndrome which typically develops in children with large congenital melanocytic nevi (LCMN) and excessive melanocyte proliferation in the leptomeninges and brain parenchyma. Malignant melanoma develops in an estimated 2.3% of patients with LCMN and 40-60% of patients with NCM. NCM-associated melanomas frequently harbor NRAS mutations with no well-established role for targeted therapy. In a retrospective, single-institution study, we reviewed eleven patients with NCM-associated CNS melanoma evaluated at Memorial Sloan Kettering Cancer Center from June 2000 to January 2020. Five patients had previously identified focal melanocytosis prior to developing melanoma. In this subgroup, the median time from identification of focal melanocytosis to melanoma diagnosis was 80 months (range: 18-200). Median age at melanoma diagnosis was 9.9 years (range: 1.1-25.3). Presentation at the time of diagnosis with CNS melanoma included headache (45%), focal deficits (45%), and seizure (18%). Eight patients had hydrocephalus (73%). Five patients presented with a focal mass (45%) and six patients had focal or diffuse leptomeningeal disease without a mass (55%). Leptomeningeal spread eventually developed in all patients. Where molecular testing was available, three melanomas had NRAS mutations and none were associated with BRAF mutations. Seven patients were treated with cancer-directed therapy including temozolomide, trametinib, ipilimumab, and nivolumab, with each therapy being administered to two patients. Radiation therapy was used in three patients, including whole brain radiation therapy and stereotactic radiosurgery. Median survival from melanoma diagnosis was 9.1 months (range: 1-60.4). The longest surviving patient was initially diagnosed with cutaneous melanoma, surviving 60.4 months after diagnosis with cutaneous melanoma and 22.7 months after diagnosis with CNS melanoma. Prognosis remains guarded in patients with NCM-associated melanoma, and further investigation is warranted to identify effective management strategies.

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