Clinical history: Paratesticular mass in a 4 year old boy
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Discussion and answer
Diagnosis: Paratesticular rhabdomyosarcoma
Encapsulated paratesticular lesion with areas composed of polygonal cells containing vesicular nuclei,prominent nucleoli and abundant brightly eosinophilic cytoplasm consistent with rhabdomyoblasts, in a myxoid stroma (C,D) and areas with spindle shaped cells containing eosinophilic cytoplasm (E,F). Many mitoses are noted.
The tumour cells are usually positive for desmin, myogenin, vimentin, myoD1, smooth muscle actin immunohistochemical stains