Malignant melanotic neuroectodermal tumour of infancy affecting the occipital squama.
T Patankar, S Prasad, A Goel, J Perumpillichira, AP Desai
Department of Radiology, Seth G. S. Medical College, Mumbai, India. , India
Department of Radiology, Seth G. S. Medical College, Mumbai, India.
An unusual case of a melanotic neuroectodermal tumour of the occipital squama, which underwent malignant transformation in a nine-month-old infant is reported and pertinent literature reviewed.
|How to cite this article:|
Patankar T, Prasad S, Goel A, Perumpillichira J, Desai A P. Malignant melanotic neuroectodermal tumour of infancy affecting the occipital squama. J Postgrad Med 1998;44:73-5
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Patankar T, Prasad S, Goel A, Perumpillichira J, Desai A P. Malignant melanotic neuroectodermal tumour of infancy affecting the occipital squama. J Postgrad Med [serial online] 1998 [cited 2022 Nov 27 ];44:73-5
Available from: https://www.jpgmonline.com/text.asp?1998/44/3/73/371
Melanotic Neuroectodermal Tumour of Infancy (MNTI) also known as melanotic progonoma is a rare, quasimalignant neoplasm occurring mostly in infants (95 percent of cases). This tumour probably reflects a primitive stage of differentiation common to many types of pigmented neuroepithelium. This tumour usually charters a benign course despite its close pathologic clinicoradiologic resemblance to other malignant round cell tumours (neuroblastoma, rhabdomyosarcoma, lymphoma, Ewing’s sarcoma). Recognition of this entity is of paramount importance as the management is different.
A 9-month-old infant presented with a right retro auricular swelling, gradually progressive over three months. There was no history of antecedent trauma, ear discharge, fever or seizures. Local examination of the swelling revealed a well defined, firm, bosselated, nontender, nonpulsatile, nonulcerated, immobile right retroauricular swelling displacing the pinna anteriorly. Transillumination test was negative. The skin over the swelling was red, warm and shiny with prominent vessels. Neurological examination was normal. Plain and contrast enhanced computerized tomographic (CT) scan of the brain showed a large, heterogeneously enhancing lesion involving right occipital squama having both intracranial and extracalvarial components [Figure:1]. Serrated configuration of the bone was the striking feature on the CT scan [Figure:2]. Based on imaging findings, the diagnosis of a malignant small round cell tumour (Metastatic neuroblastoma, Ewing’s sarcoma, rhabdomyosarcoma, lymphoma) involving the occipital squama was made. Open biopsy of the tumour revealed a hypervascular, hard bony component and a firm greyish red superficial extracalvarial component. Histopathological examination showed irregular alveolar spaces lined by cuboidal cells containing varying amounts of melanin. Isolated nests of small round poorly differentiated cells resembling those of neuroblastoma were seen [Figure:3]. These cells had scant cytoplasm, prominent nucleoli and hyperchromatic nuclei. Nuclear atypia and hyperchromasia in these cells conclusively proved the tumour to be a malignant melanotic neuroectodermal tumour. Extracranial component was excised. In the immediate postoperative period, the patient had mild, transient peripheral facial nerve paresis, which resolved in four days. Subsequently the patient was referred for chemotherapy, which included alternate cycles of cyclophosphamide and doxorubicin every 21 days for four months. There was complete resolution of the tumour and the patient has been symptomfree for the last one and a half years.
Majority of MNTI affect infants below three months of age. No definite sex predilection exists. Various histogenetic theories have been proposed since the original description of the tumour by Krompecher (1918) who described it as congenital melanocarcinoma. Tissue culture, immunohistochemical and ultrastructural studies have pointed to the neural crest origin of the tumour. Tumour elaboration of vanillyl mandelic acid (VMA), and the presence of neuron specific enolase in tumour cells is identical to that found in neuroblastoma and phaeochromocytoma MNTI is unique in its ability to synthesise melanin and differ from other pigmented neoplasms in that it characteristically affect infants at the classical sites. Melanin producing cells have been described in tumours of the central nervous system such as medulloblastoma, schwannoma, meningioma, ependymoma and choroid plexus carcinoma. Head and neck region account for over 90% of cases. While maxilla (anterior maxillary alveolar ridge) is the classical and most common site of this neoplasm (68.8%), it also uncommonly occurs in sku11(10.8%), mandible(5.8%) and brain(4.3%). Rare sites of origin include mediastinum, extremities, epididymis, ovary and uterus. Though MNTI has a relatively benign course, malignant transformation occurs in 34% of cases. Tumour recurrences have been noted in 1015% of cases.
The striking feature in our case was the serrated configuration of the occipital squama, which usually occurs in round cell tumours affecting the bone. Another interesting feature is the malignant transformation of this tumour in this infant. Malignant MNTI have been reported in maxilla, mandible, cerebellum, uterus, ovary, epididymis and femur. To our knowledge the present case represents the first instance of malignant change occurring in MNTI affecting the occipital squama. Malignant MNTI needs to be managed as neuroblastoma.
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