14 January 2010 Case of the Week #165


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Thanks to Dr. Karen Fritchie, University of North Carolina at Chapel Hill (USA), for contributing this case.  To contribute a Case of the Week, follow the guidelines on our Case of the Week page.


Case of the Week #165


Clinical History


A 4 month old child was found to have a midline skull lesion.  She was the product of an uneventful pregnancy, and she had no other medical issues.  The lesion was excised.


Micro images:


Low power                              High power


What is your diagnosis?



























Pigmented neuroectodermal tumor of infancy




This uncommon, rapidly growing mesenchymal tumor typically occurs in the bones of the jaw or skull in infants in their first year of life (eMedicine).  It is a biphasic tumor with tubular or alveolar patterns.  It consists of large melanin-containing cells with abundant cytoplasm and pale nuclei, surrounding nests of smaller neuroblast-like cells possessing scant or fibrillar cytoplasm.  There is usually minimal mitotic activity, and no atypia.


The large cells are immunoreactive for keratin and HMB45.  The smaller cells are usually immunoreactive for CD57/Leu7 and NSE.  Although the tumor is of neuroectodermal origin, both cell types are usually negative for S100 (Am J Surg Pathol 1993;17:566).  Ultrastructurally, the pigmented cells contain melanosomes, and the neuroblast-like cells contain neurosecretory granules and cytoplasmic processes.


Pigmented neuroectodermal tumor of infancy was historically called melanotic progonoma or retinal anlage tumor based on the suspected cell of origin.  In 1966, Borello and Gorelin reported a patient with this tumor and high urinary excretion of vanilmandelic acid, suggesting a neuroectodermal origin (Cancer 1966;19:196), which has subsequently been confirmed.  


The differential diagnosis includes neuroblastoma and other small round blue cell tumors, as well as melanoma.  These malignant tumors typically lack the clinical presentation of a jaw or skull tumor in infants, exhibit prominent necrosis, atypia and mitotic figures, and lack the biphasic pattern of pigmented neuroectodermal tumor of infancy.


Treatment is excision with negative margins.  Recurrence has been reported in 37% of cases, with metastases in 7%, although no prognostic factors have been identified (Fetal Pediatr Pathol 2006;25:59). 



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