Collision tumor of anaplastic oligodendroglioma and gangliocytoma: a case report

A Patient With Epilepsy, Ganglioglioma, and Oligodendroglioma With Anaplastic Foci in the Same Left Frontoparietal Lesion: A Case Report

Gangliogliomas are central nervous system (CNS) tumors with a neuronal and glial component considered grade 1 according to the World Health Organization (WHO) classification. On the other hand, oligodendrogliomas are diffuse infiltrating gliomas (CNS WHO grade 2 or 3) characterized by both an isocitrate dehydrogenase mutation and 1p/19q co-deletion. There have been some cases with the coexistence of these two tumors. Here, we present the case of a low-growing left frontoparietal brain tumor with a definite diagnosis of ganglioglioma (CNS WHO grade 1) and oligodendroglioma (CNS WHO grade 2) with areas of anaplastic oligodendroglioma (CNS WHO grade 3) in a patient with long-standing epilepsy.

Metastatic melanoma with striking adenocarcinomatous differentiation illustrating phenotypic plasticity in melanoma

We report on the highly unusual case of a 75-year-old woman who developed a biphasic right axillary mass of apparent melanoma and adenocarcinoma 13 years after a diagnosis of primary melanoma on her right upper back. The differential diagnosis included a collision tumor and metastatic melanoma with adenocarcinomatous transdifferentiation. We utilized immunohistochemical staining, DNA sequencing, and comparative genomic hybridization (CGH) to characterize this unusual tumor. By immunohistochemistry, the melanomatous component was positive for S100 and Melan-A, and had patchy positivity for cytokeratin. The adenocarcinomatous component was negative for melanoma markers, but was strongly positive for cytokeratin. In addition, the glandular component was positive for CDX-2 and Ber-EP4, giving the distinct histologic and immunohistochemical impression of a gastrointestinal metastasis nested within a deposit of metastatic melanoma. Clinical and radiologic workup failed to reveal a primary gastrointestinal malignancy. Molecular genetic analysis, including DNA sequencing and CGH, revealed that both areas contained an identical NRAS Q61K mutation and had highly similar CGH profiles, including gains of chromosome 1q and losses of 1p, 4, 9, and 10, which are archetypical of melanoma. The NRAS mutation was also identified in a deposit of metastatic melanoma resected 12 years earlier, but was not seen in the patient's nontumorous tissue, indicating that it was somatically acquired. Genetic analyses demonstrate that 2 morphologically distinct tumors arose from a common ancestor melanoma cell that harbored an NRAS mutation and subsequently divergently evolved by the acquisition of additional genomic alterations. Our findings illustrate the ability of molecular analyses to resolve lineage in complex neoplasms and illustrate the phenotypic plasticity of cancer cells.