Created by SEAP-IAP Sociedad Española de Anatomía Patológica on May 11, 2013 11:18:28 AM, Last modified by SEAP-IAP Sociedad Española de Anatomía Patológica on May 18, 2013 8:43:26 PM
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A 42 years-old man presented with a growing mass in the right maxillary sinus, of 4 months duration. Following biopsy, the patient was treated with chemotherapy. The tumour initially regressed, recurring 4 months later. (Case kindly provided in consultation by Drs. Prantel and Nerlich, Institut für Pathologie, Klinikum Schwabing, Munich, Germany).
This sinonasal tumour is made up, in about 85-90%, of structures corresponding to a yolk sac tumour depicting a mixture of reticular and solid patterns. The reticular pattern shows the typical features of an endodermal sinus tumour, the solid pattern being formed by large nests of cells differentiating towards primitive intestine. Surrounding both patterns there are variable amounts of reactive stromal component. In addition, at one of its two poles, the yolk sac tumour merges together with an immature teratom composed of primitive ducts and mesenchyme that comprise about 10 to 15% of the whole neoplastic lesion. This neoplastic merging recapitulates the continuity of the yolk sac with the normal embryo seen by the 5th week of gestation. Therefore, we are facing one single combined tumour with two poles of divergent developmental differentiation.
COMBINED SINONASAL YOLK SAC TUMOUR AND IMMATURE TERATOMA.
The main differential diagnosis of our case is sinonasal teratocarcinosarcoma. The diagnosis of teratocarcinosarcoma requires the mixture of immature and mature structures; the latter are not seen in our tumour. Also not seen in the current case are structures suggesting seminoma or embryonal carcinoma.
The challenge behind the interpretation of the findings in this sinonasal tumour is not only whether we are facing a single combined tumour with two poles of divergent differentiation, composed of a large pole of yolk sac tumour and a small pole of immature teratoma, but also whether there is in addition a third tumour component, namely cylindric-transitional cell carcinoma, as described by Manivel et al in 1986.
In my view there is no detectable evidence of transitional cell carcinoma component in the case under discussion. This is based on the following:
The entity for many years known as cylindric-transitional cell carcinoma of the sinonasal tract has been shown recently to be an HPV related, p16 positive, sinonasal squamous cell carcinoma (El-Mofty SK et al Am J Surg Pathol 2005; 29:1367) (Alos et al Cancer 2009; 115:2701), and the case under discussion fails to show in its solid (epithelial) component the prominent (+++) p16 positive reaction typical of HPV related carcinomas. Viewed with the eyes of the nowadays increased expertise in these tumours, the tumour nests looking alike transitional cell carcinoma in our case fit quite well with the solid nests of primitive intestinal pattern of yolk sac tumour, as documented by Roth LM et al, Int. J. Gynecol Pathol 2011; 30:442. For this type of tumour, in addition to surgical removal, the previous authors recommend platinum-based chemotherapy.