PMC7997754_01
(a) This MRI image was taken at first presentation in 2011. It showed a large lobulated heterogeneous mass extending from the middle of the left arm down to the middle of forearm, measuring 29 x 9 x 9 cm. (b) The last MRI imaging done dated on January 2018. No evidence of circumscribed mass lesion or abnormal enhancement to suggest tumor recurrence. No new lesions identified.
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The radial neurovascular bundle cannot be separated from the lesion (Figure 1(a)). He received three cycles of chemotherapy (doxorubicin and ifosfamide) followed by radiation therapy 60 Gray (Gy) units over 30 fractions that ended in 2011, with marked improvement of his lesions (Figure 1(b)).
(a) Photomicrograph showing a neoplasm predominantly composed of spindle cells arranged in interlacing fascicles of alternating hypercellular and hypocellular areas (marbleization). H&E x40. (b) The nuclei are pleomorphic, hyperchromatic, and mitotically active. H&E x200. (c) Focus within the tumor shows rhabdomyoblastic differentiation. H&E x100. (d) The glandular components seen lined by malignant columnar epithelial cells. H&E x400.
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Histopathology slides from the referring hospital were reviewed, The tumor was predominantly composed of spindle cells arranged in interlacing fascicles, with a pattern of alternating dense and hypodense areas giving the so-called marbleized appearance (Figure 2(a)), with pleomorphic, hyperchromatic nuclei, and increased mitotic activity (Figure 2(b)). There were several foci of rhabdomyoblastic differentiation featuring large rhabdomyoblasts with abundant eosinophilic cytoplasm (Figure 2(c)). Some fields exhibit glandular differentiation featuring glands lined by malignant columnar epithelial cells, with mitotic figures and large pleomorphic nuclei (Figure 2(d)).
(a) Immunohistochemical (IHC) staining for S100 protein shows patchy nuclear and cytoplasmic expression. (b) Rhabdomyoblastic cells are strongly positive for desmin. (c) Within the foci of rhabdomyoblastic differentiation, there are cells showing nuclear myogenin expression. (d) The glandular components are highlighted by pan-cytokeratin positivity.
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Immunohistochemically, the spindle cell component showed patchy nuclear and cytoplasmic S100 protein expression (Figure 3(a)), while the rhabdoid cells were strongly positive for desmin (Figure 3(b)), and within the desmin-positive areas, there were cells showing nuclear myogenin expression (Figure 3(c)). The malignant epithelial cells of the glandular component were positive for pan-cytokeratin (pan-CK) (Figure 3(d)), but were negative for chromogranin and synaptophysin.