Currently characteristic genetic or molecular abnormalities have not been identified in MNTI. One report indicated that 1 of the 3 cases tested had BRAF-V600E mutation.
The differential diagnosis of MNTI includes other small round blue cell tumors of childhood, especially neuroblastoma, Ewing sarcoma, alveolar rhabdomyosarcoma, and lymphoma, in addition to melanogenic tumors, including malignant melanoma and clear cell sarcoma of soft tissue.
Lack of the primitive-appearing neurogenic cells is a very important morphologic key to distinguish it from MNTI. Clear cell sarcoma is associated with recurrent characteristic translocations, mainly t(12;22)(q13;q12), resulting in EWS-ATF1 chimeric gene, and less commonly t(2;22)(q34;q12).
Although generally considered benign, the biologic behavior of MNTI is not fully understood.
Molecular profiling of a large cohort of MNTI cases may aid in shedding light on this rare tumor biology.
Melanotic neuroectodermal tumor of infancy (MNTI) of the head and neck: a French multicenter study.
MNTI: Melanocytic neuroectodermal tumor of infancy.
Caption: FIGURE 2: In vivo appearance of MNTI, demonstrating significant progression from 1.3 cm nodule on T1-contrasted sequence MRI two weeks prior.
Caption: FIGURE 3: Ex vivo appearance of MNTI. Notice the dark blue characteristic and well-circumscribed nature of the lesion.