CHAPTER X CHAPTER 4 - Cancer et environnement

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often have a grey-white cut surface and may show areas of dark pigmentation. Histopathology There is usually a dual population of cells. Larger melanin containing epithelioid cells form nests, cords and glandlike structures. Smaller neuroblast-like cells with high nuclear to cytoplasmic ratios are closely apposed to the larger cells. Mitoses may be identified, especially in the small cell component. Immunoprofile Melanotic neuroectodermal tumour expresses a variety of epithelial, melanocytic and neural markers {1273, 2062}. The large cells typically stain for cytokeratins and HMB45. S100, neuron specific enolase, synaptophysin, glial fibrillary acidic protein and desmin may also be seen. Ultrastructure Electron microscopy shows that the small neuroblastic cells have cytoplasmic processes with microtubules and occasional dense core granules. The larger cells show evidence of both epithelial and melanocytic differentiation with desmosomal attachments and premelanosomes and mature melanosomes, respectively {2062}. Histogenesis The histogenesis of melanotic neuroectodermal tumour is unknown although it is thought to be a dysembryogenetic neoplasm which is nearly always congenital. Fig. 4.106 Desmoplastic small round cell tumour. Prognosis Melanotic neuroectodermal tumour of epididymis generally behaves in a benign fashion but may recur locally. Two examples have demonstrated lymph node metastasis, either inguinal or retroperitoneal {566,1235} No distant metastasis has been documented. Desmoplastic small round cell tumour Definition A malignant serosa related small round cell tumour with an epithelial growth pattern in a desmoplastic stroma. ICD-O code 8806/3 Sites of involvement The pelvic and abdominal cavities are mostly involved followed by the paratesticular region {528,857,1971,2365}. Clinical features The patients range in age from 5-37 Fig. 4.107 Desmoplastic small round cell tumour. Anti desmin staining. years. They present with hydroceles or scrotal masses without hydroceles. Macroscopy The tumours are firm and present as multiple varying sized nodules ranging from a few millimeters to 9.5 cm. The nodules are intimately associated with the tunica. Histopathology These consist of well delineated nests and anastomosing cords of rather uniform small cells supported by a prominent desmoplastic stroma. The nuclei are round, oval or elongated, or grooved with finely dispersed chromatin and one or two small nucleoli. The scant cytoplasm is light or eosinophilic and may contain glycogen. Cell borders are prominent. Normal and abnormal mitoses are common. Single cell necrosis and comedo like necrosis are commonly present. Occasionally, squamous metaplasia and glandular or tubular formations can be seen. One case showed sparse intraand extra-cellular mucin production. A B Fig. 4.108 Desmoplastic small round cell tumour. A Note the small nests in dense stroma. B Higher magnification shows nests of small cells surrounded by desmoplastic stroma. 272 Tumours of the testis and paratesticular tissue
Fig. 4.109 Desmoplastic small round cell tumour DSRCT. Diagrammatic representation of chromosomal breakpoints in DSRCT with t(11;22)(p13;q12). Fig. 4.110 Desmoplastic small round cell tumour DSRCT. Diagrammatic representation of chromosomal breakpoints in DSRCT with EWS-WT1 fusion transcript types. All chromosome 11 translocation breakpoints involve intron 7 of WT1, suggesting that the preservation of the last three zinc finger motifs of WT1 is crucial to the sarcomagenesis. The majority of chromosome 22 breakpoints involve the intron 7 of EWS, and very infrequently introns 8 and 9. Immunoprofile The tumour shows dual differentiation with keratin and desmin expression. The desmin reactivity shows a dot pattern. NSE, EMA and vimentin are also positive. About 91% of tumours express EWS- WT1 gene fusion transcript {2334}. Differential diagnosis Macroscopically, the tumour is similar to mesothelioma, but by microscopy it has to be separated from other small round cell tumours involving the paratesticular region. These include embryonal rhabdomyosarcoma and lymphoma. They do not show the desmoplastic stroma and nested growth pattern. Immunohistochemistry will be helpful. Genetics DSRCT is characterized by a specific chromosomal abnormality, t(11;22) (p13;q12), {240,2218,2314} unique to this tumour, involving two chromosomal regions previously implicated in other malignant developmental tumours. The translocation results in the fusion of the Ewing sarcoma gene, EWS, on 22q12 and the Wilms' tumour gene, WT1, on 11p13 {564,858,1423}. Interestingly, the most common primary site of DSRCT, the serosal lining of body cavities, has a high transient fetal expression of WT1 gene. WT1 is expressed in tissues derived from the intermediate mesoderm, primarily those undergoing transition from mesenchyme to epithelium, in a specific period of development {2113,2139}. This stage of differentiation is reminiscent of DRCT with early features of epithelial differentiation. The most commonly identified EWS-WT1 chimeric transcript is composed of an in-frame fusion of the first seven exons of EWS, encoding the potential transcription modulating domain, and exons 8 through 10 of WT1, encoding the last three zinc-finger of the DNA binding domain. Rare variants including additional exons of EWS occur {102}. Intranuclear chimeric protein can be detected and shown to contain the carboxy terminus of WT1 {856}. Detection of the EWS-WT1 gene fusion and chimeric transcript serves as a sensitive and specific marker for DSRCT and has proven useful in the differential diagnosis of undifferentiated small round cell tumours of childhood {856}. Prognosis Most patients develop peritoneal and retroperitoneal disease within 2 years and die within 3-4 years. Metastases involve liver and lungs. One patient with a solitary tumour involving the epididymis developed retroperitoneal disease 18 years post orchiectomy. Mesenchymal tumours of the scrotum, spermatic cord, and testicular adnexa ICD-O codes Lipoma 8850/0 Leiomyoma 8890/0 Neurofibroma 9540/0 Granular cell tumour 9580/0 Male angiomyofibroblastomalike tumour (cellular angiofibroma) 8826/0 Calcifying fibrous (pseudo) tumour Fibrous hamartoma of infancy Liposarcoma 8850/3 Leiomyosarcoma 8890/3 Malignant fibrous histiocytoma 8830/3 Rhabdomyosarcoma 8900/3 Incidence Scrotal mesenchymal tumours are rare and their etiology is poorly understood. The four most frequently reported benign tumours are haemangiomas, lymphangiomas, leiomyomas and lipomas. In our experience, many lesions designated as lipoma of the spermatic cord are reactive accumulations of fat related to hernial sac. Other benign lesions include a variety of nerve sheath tumours (neurofibroma {1182}, schwannoma and granular cell tumour). Male angiomyofibroblas- Tumours of paratesticular structures 273
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CHAPTER 4X Tumours of the of the Te
Page 3 and 4:
TNM classification of germ cell tum
Page 5 and 6: Germ cell tumours P.J. Woodward A.
Page 7 and 8: senting symptom: back or abdominal
Page 9 and 10: A B Fig. 4.03 Germ cell tumours gen
Page 11 and 12: process at all {1524}. In addition,
Page 13 and 14: A B Fig. 4.12 Comparison of morphol
Page 15 and 16: small tumour insufficient to produc
Page 17 and 18: A B C Fig. 4.22 Seminoma. A Pseudog
Page 19 and 20: A B Fig. 4.27 Spermatocytic seminom
Page 21 and 22: Differential diagnoses Differential
Page 23 and 24: Histologic patterns Microcystic or
Page 25 and 26: A Fig. 4.40 Yolk sac tumour. A Pleo
Page 27 and 28: Teratoma Teratomas are generally we
Page 29 and 30: A B C Fig. 4.49 Teratoma. A Teratom
Page 31 and 32: A B Fig. 4.52 Teratoma with somatic
Page 33 and 34: A B Fig. 4.59 Mixed germ cell tumou
Page 35 and 36: A B C Fig. 4.64 Leydig cell tumour.
Page 37 and 38: A Fig. 4.69 Androgen insensitivity
Page 39 and 40: tinguished from Sertoli cell nodule
Page 41 and 42: ound and have spherical, regularly
Page 43 and 44: Tumours containing both germ cell a
Page 45 and 46: Miscellaneous tumours of the testis
Page 47 and 48: Lymphoma and plasmacytoma of the te
Page 49 and 50: Tumours of collecting ducts and ret
Page 51 and 52: Tumours of paratesticular structure
Page 53 and 54: Epidemiology Nodular mesothelial hy
Page 55: A B Fig. 4.104 Papillary cystadenom
Page 59 and 60: Fig. 4.115 Leiomyosarcoma. Coronal,
Page 61 and 62: Secondary tumours C.J. Davis Defini
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CHAPTER X CHAPTER 4 - Cancer et environnement

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