case_images: PMC10569689_01
case_images: (A) The left breast exhibited nipple inversion and is filled with a large combined mass. (B) The broken surgical piece of the mass. (C) The surgically removed mass is longitudinally incised and measures 13.0 cm x10.0 cm x 9.0 cm in diameter. (D) The histopathological section (hematoxylin and eosin staining) of the tissue from the surgical piece. (E) Immunohistochemistry results revealed the expression of Desmin, which is considered a characteristic feature of RMS. (F) Immunohistochemistry results demonstrated the expression of Myogenin.
case_images: fonc-13-1233208-g001.jpg
case_images: PMC10569689_01_fonc-13-1233208-g001.jpg
case_images: f1
case_images: A 13-year-old female patient was initially referred to our hospital due to the presence of a large mass in her left breast, accompanied by nipple inversion ( Figure 1A ). Given the suspicion surrounding the pathological attributes of the mass, coupled with the patient's young age, a comprehensive excision of the mass was performed ( Figures 1B, C ). The pathological findings ultimately confirmed that the mass was a combination of MPT with heterogenous differentiation, specifically rhabdomyosarcoma, as depicted in  Figure 1D . Desmin ( Figure 1E ), and positive staining for Myogenin ( Figure 1F ). Additionally, the Ki67 index was determined to be 75%. Desmin and myogenin were identified as useful markers for differential diagnosis.
case_images: (A) The recurrent mass presented a diameter of 5.7 cm x 5.5 cm x4.5 cm in the left breast within 2 months. (B) PT x 40:the histopathological section (hematoxylin and eosin staining) of the tissue from the second surgical piece.
case_images: fonc-13-1233208-g002.jpg
case_images: PMC10569689_01_fonc-13-1233208-g002.jpg
case_images: f2
case_images: Regrettably, local recurrence occurred rapidly, with the reappearance of the mass in the left breast resembling a ping pong ball and exhibiting aggressive growth on 3 October ( Figure 2A ). Immunohistochemical analysis demonstrated weakly positive expression of SMA and AE1/AE3, positive expression of Desmin and CD34, and an elevated Ki67 index of 85%  Figure 2B .
case_images: (A) The chest CT imaging presented the multiple pulmonary nodules in the right and left lung, with the biggest metastasis measuring nearly 2 cm. (B) The 18F-FDG PET/CT showed an increased FDG uptake of the largest left pulmonary nodule (inferior lobe; SUVmax, 3.9) and mild FDG uptake of the multiple pulmonary nodules.
case_images: fonc-13-1233208-g003.jpg
case_images: PMC10569689_01_fonc-13-1233208-g003.jpg
case_images: f3
case_images: Unfortunately, about weeks ago, pulmonary nodules were found by the computer tomography (CT) and positron emission tomography/computed tomography (PET/CT) ( Figures 3A, B ), which were suspected to be the lung metastasis.