WNT‐activated medulloblastoma with melanotic and myogenic differentiation: Report of a rare case

Abstract

Medulloblastoma (MB) with melanotic and myogenic differentiation, previously known as melanotic medullomyoblastoma, is an extremely rare histological variant of MB showing melanocytic as well as skeletal muscle differentiation. Only 10 cases of this rare tumor have been reported in the literature to date. We report this case of a 2-year-old male child who presented with a midline cerebellar mass, which on histopathological examination showed classic MB intermixed with cells containing melanin pigment, along with rhabdomyoblasts, spindle cells and occasional strap cells, which corresponded to WNT subgroup on molecular classification. The cell of origin of this MB variant is likely to be neural crest-derived stem cells which are capable of multilineage differentiation. Significant findings from previous reports and important differential diagnoses are discussed. Documentation of these tumors is important to characterize the clinical behaviour and to identify distinct genetic features, if any.

Melanotic Neuroectodermal Tumor of Infancy (MNTI) and Pineal Anlage Tumor (PAT) Harbor A Medulloblastoma Signature by DNA Methylation Profiling

“…Interestingly, a neural crest origin has been proposed based on the ultrastructure and proteomic features of its pigment resembling oculocutaneous melanin, including premelanosomes (rather than neuromelanin) [38]. Recently, Rajeshwari et al reported a WNT-activated medulloblastoma with melanotic differentiation and speculated about the potential contribution of neural crest cell progenitors into their pathobiology [39].…”

Sequential improvement in paediatric medulloblastoma outcomes in a low-and-middle-income country setting over three decades

“…In addition, the ability to perform molecular studies will need to be addressed, as these are providing increasingly powerful evidence for a paradigm shift in the way MBs are approached. 37 http://www.sajo.org.za Open Access support or expertise, historical feedback, data review and paper assessment. J.P. was the primary supervisor and paediatric radiation oncology support/guidance.…”

Squash cytology of a case of medulloblastoma with myogenic differentiation

“…[4][5][6] Little is known about the molecular classification of these rare medulloblastoma variants and only a few reports have elaborated on their molecular subtyping. [6][7][8] The largest extant series of medullomyoblastomas by Gupta et al concluded that these tumors are not easily classified by the genetic subtypes of medulloblastoma, at least using immunostain surrogates of molecular characteristics. Molecular tests to establish whether these tumors belonged to group 3 or group 4 were apparently not done, and one can infer that these tumors were likely not SHH-activated or Wnt-activated.…”

“…Medulloblastoma with myogenic differentiation and melanotic differentiation are considered to be morphological patterns which could be associated with any of the four histological categories 1 . Rarely, tumors can have both myogenic and with melanotic differentiation, as evidenced by a few case reports in literature 4‐6 . Little is known about the molecular classification of these rare medulloblastoma variants and only a few reports have elaborated on their molecular subtyping 6‐8 .…”

“…Rarely, tumors can have both myogenic and with melanotic differentiation, as evidenced by a few case reports in literature 4‐6 . Little is known about the molecular classification of these rare medulloblastoma variants and only a few reports have elaborated on their molecular subtyping 6‐8 . The largest extant series of medullomyoblastomas by Gupta et al concluded that these tumors are not easily classified by the genetic subtypes of medulloblastoma, at least using immunostain surrogates of molecular characteristics.…”