Urachal neuroblastoma: first case report

Pediatr Radiol (1999) 29: 320±321 Ó Springer-Verlag 1999

Philippe Clapuyt Christine Saint-Martin Philippe De Batselier B. Brichard F. X. Wese S. Gosseye

Received: 3 August 1998 Accepted: 30 November 1998

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P. Clapuyt ( ) × C. Saint-Martin × P. De Batselier Department of Paediatric Radiology, Saint Luc University Hospital, Av Hippocrate 10, B-1200 Brussels, Belgium

Urachal neuroblastoma: first case report

F. X. Wese Department of Urology, Saint Luc University Hospital, Brussels, Belgium S. Gosseye Department of Anatomopathology, Saint Luc University Hospital, Brussels, Belgium

Abstract Tumours of the urachus are exceptional in children. They represent 0.01 % of all tumours and consist of mucosecretory adenocarcinoma and, more rarely, transitional cell carcinoma. We report a 6month-old child with a urachal mass which, following biopsy, was shown to be a neuroblastoma.

B. Brichard Department of Paediatric Haematooncology, Saint Luc University Hospital, Brussels, Belgium

Introduction Tumours of the urachus are exceptional in children. They represent 0.01 % of all tumours and consist of mucosecretory adenocarcinoma and, more rarely, transitional cell carcinoma. We report a 6-month-old child with a urachal mass which, following biopsy, was shown to be a neuroblastoma.

Case report A 6-month-old child was referred for further investigation of an antenatally diagnosed multicystic dysplastic kidney. US confirmed a right multicystic dysplastic kidney associated with an anomaly of insertion of the right lower ureter into the right seminal vesicle. There was also a hypoechoic mass containing small echogenic foci sited in the midline and intimately related to the bladder dome (Fig. 1). A malformation of the urachus was diagnosed; the absence of clinical signs of infection suggested the possibility of a tumour. At surgery, right nephrectomy confirmed the right multicystic dysplastic kidney and resection of the mass revealed it to be neuroblastoma (Fig. 2). US, chest X-ray, bone marrow biopsy, MIBG

scintigraphy and serum alpha-fetoprotein and neurone-specific enolase levels were normal. No supplementary treatment was given and, 18 months later, the child is in excellent health.

Discussion The diagnosis of malignancy of the urachus is often delayed because of the lack of clinical signs. Tumour in this location is very rare, mainly affecting adults in the fifth and sixth decades (range 5±80 years) and is predominant in men (60±70 %) [1±5]. Most (70 %) are mucin-producing adenocarcinoma; more rarely, it is nonmucin-producing adenocarcinoma (15 %) or transitional cell carcinoma (15 %) [6, 7]. A unique case of endodermal sinus (yolk sac) tumour of the urachus in a 2year-old child has been described [8]. We have not found a description of urachus neuroblastoma. The urachus is the vestigial remnant of the allantois, which is also a germinal structure containing multipotent cells [8, 9]. No study has proven with certainty the presence of neural crest cells in the urachus. It is there-

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a Fig. 2 Histology reveals that the urachal mass is composed of lobules separated by fibrous septa. The lobules comprise small, round cells with inconspicuous cytoplasm and hyperchromatic nuclei disseminated in a finely fibrillary material. Some cells are slightly larger with more obvious rounded or angular cytoplasm and a vesicular nucleus

fore impossible to say whether it is a primitive or secondary site. Our investigations failed to identify any other tumour deposit, but we know that microscopic primitive neuroblastoma, even undetectable by scintigraphy, can give macroscopic secondary disease.

b Fig. 1 a, b US of the urachal mass in contact with the bladder. There are hypoechoic and hyperechoic foci (arrowheads)

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