Protumorigenic M2-like phenotype cell infiltration in the melanotic neuroectodermal tumor of infancy

Melanotic Neuroectodermal Tumour of Infancy

Melanotic neuroectodermal tumour of infancy (MNTI) is a locally aggressive neoplasm of neural crest origin. It is primarily a paediatric tumour, and 95% of the cases occur in children below 1 year. The tumour mainly affects the head and neck region. It shows a predilection for the craniofacial sites and the most common site affected is anterior maxilla. Microscopically, it is characterized by a biphasic population of neuroblastic cells and pigmented epithelial cells. Although generally considered as a benign tumour, it can invade the adjacent muscle and bone, causing destruction of the involved site. The rapidity in growth and the aggressive clinical behaviour of the tumour can be deceptive and hence lack of familiarity with the clinical characteristics of the tumour may often lead to an erroneous diagnosis of malignancy. The treatment of choice for MNTI is excision, and it is usually curative. Extensive surgery in a child may interfere with the normal growth and development of the facial structures and reconstruction can be very challenging in infants. Hence, early diagnosis is critical for the effective management. Clinical findings, histopathological features, and differential diagnosis of a classic case of melanotic neuroectodermal tumour of infancy are discussed.

Melanotic Neuroectodermal Tumor of Infancy

Context.—

Melanotic neuroectodermal tumor of infancy, albeit rare and generally regarded as benign, is an important tumor to recognize because of its rapid growth, potential for local recurrence, and small round blue cell morphology, which can lead to misdiagnosis of a malignant neoplasm.

Objective.—

To review its clinical presentation and immunomorphologic findings, and discuss common entities in the differential diagnosis.

Data Sources.—

The study involved PubMed searches, including multiple review articles, case studies, retrospective studies, selected book chapters, and University of Michigan cases.

Conclusions.—

Melanotic neuroectodermal tumor of infancy most commonly occurs in the bones of the head and neck region during the first year of life, but it can also present in other locations, including the central nervous system, testes, ovaries, and subcutaneous soft tissues. Histologically, it is composed of a biphasic population of cells, consisting of epithelioid melanin-producing cells and primitive neurogenic cells in a fibrocollagenous stroma. These microscopic findings, especially in small biopsies, can lead to a broad differential diagnosis that includes malignant small round blue cell tumors and malignant melanoma. Melanotic neuroectodermal tumor of infancy commonly has an infiltrative growth pattern, and anatomic constraints often lead to incomplete resection and local recurrence, requiring multiple surgical operations. Because melanotic neuroectodermal tumor of infancy can mimic a more aggressive and aggressively treated malignancy, recognition of this rare tumor is very crucial for pathologists.

Clinical and immunohistochemical study of melanotic neuroectodermal tumor of infancy in the maxilla

Melanotic neuroectodermal tumor of infancy is a rare and fast-growing neoplasm. In this study, we describe the case of a 6-month-old female patient, who presented swelling in the anterior maxilla. Tomographic reconstruction showed an unilocular hypodense and expansive area associated with the upper right central primary incisor. The presumptive diagnoses were dentigerous cyst, adenomatoid odontogenic tumor, melanotic neuroectodermal tumor of infancy and rhabdomyosarcoma, and an incisional biopsy was performed. Microscopically, the lesion revealed a biphasic cell population, consisting of small, ovoid, neuroblastic-like cells and epithelioid cells containing melanin. Immunohistochemically, the melanocyte-like component was strongly and diffusely positive for HMB-45 and Melan-A, but weakly positive for S100. Based on these findings, definitive diagnosis of melanotic neuroectodermal tumor of infancy was established. Then, enucleation of the lesion was performed by careful curettage. After 2 year follow-up, no clinical or radiographical evidence of recurrence was verified. The present case highlights the importance of early diagnosis and therapeutic intervention at the appropriate time to achieve a favorable outcome for the patient.

Prenatal Diagnosis of a Melanotic Neuroectodermal Tumor of Infancy (MNTI): A Case Report With a Favorable Outcome After Chemotherapy Failure and Incomplete Resection

We present the case of a woman referred to our department at 34 weeks of pregnancy with a fetal ultrasonographic scan showing a mass that had developed within the right maxilla with invasion of the orbit. A retrospective examination showed that this tumor had been present since the 12th week of pregnancy. At 39+4 weeks of gestation, a boy was born. He presented a black firm aspect in the maxilla. A computed tomographic scan and magnetic resonance imaging revealed a soft tissue swelling over the right maxilla, extending into the orbit but without invasion of the globe. Surgical biopsy confirmed a melanotic neuroectodermal tumor of infancy. The pathologic examination did not show any neuroblast-like component on the hematoxylin eosin saffron staining. Because of the extension and the size of the lesion, neoadjuvant chemotherapy was carried out. At day 21, the patient received 1 cycle of low-dose cyclophosphamide and vincristine, 2 cycles of etoposide and carboplatin, and thereafter 1 cycle of cyclophosphamide, adriamycin, and vincristin because the lesion kept growing. After stabilization of the size of the tumor, at 4 months, a maxillectomy and partial resection of the orbital floor and lateral orbital wall was performed on the patient. As a complete resection would have required orbital exenteration, surgery was performed deliberately incomplete leaving a macroscopic residue (R2). At 2.5 years of follow-up, the patient showed complete remission with no lesions evident on magnetic resonance imaging.