PMC5457929_01
MR images of the penis before treatment. (a) A sagittal section of a STIR T1-weighted image shows a soft tissue mass with mild heterogeneous high intensity in the dorsal area of the glans penis and shaft. (b) A coronal section of a diffusion-weighted image shows high-intensity swelling of the foreskin.
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T1-weighted images (Fig. 1a), mild heterogeneous low intensity on T2-weighted images, and high intensity on diffusion-weighted images. The remarkable swelling of his foreskin was also present (Fig. 1b).
The histopathological findings of the biopsied sample obtained from a nodule in the shaft and pituitary stalk. (a) - (c) are pathological pictures of the nodule in the shaft. (d) - (f) are pathological pictures of the mass in the pituitary stalk. (a) Numerous abnormal cells with scant cytoplasm and clear nucleoli were densely occupied with a scattered starry sky-like appearance in the nodule [Hematoxylin and Eosin (H&E) staining, original magnification of objective lens, 40x]. (b, e) In immunohistochemical staining, CD20 was positive in the abnormal cells (original magnification of objective lens, 20x). (c, f) The Ki-67 index was very high (original magnification of objective lens, 20x). (d) The numerous abnormal cells seen in the nodule of the shaft densely infiltrated the pituitary stalk (H&E staining, original magnification of objective lens, 40x).
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Biopsy of the nodules on the shaft of his penis showed that numerous abnormal cells with scant cytoplasm and clear nucleoli were densely occupied with a scattered starry sky-like appearance mainly involving the subcutaneous tissue and dermis (Fig. 2a). An immunohistochemical analysis revealed that these abnormal cells were positive for CD20 (Fig. 2b), CD10, and BCL6, and negative for CD5 and BCL2, which confirmed the diagnosis of DLBCL, germinal center B cell type according to Hans' criteria. The Ki-67 index was very high (Fig. 2c). Open biopsy of the mass lesion confirmed the diagnosis of DLBCL with the same immunohistochemical phenotype as the initial nodules of his penis (Fig. 2d-f).
Whole-body PET-CT scans. (a) Abnormal accumulation of FDG in the penis was only found before the treatment. (b) No abnormal accumulation of FDG was found in the whole body at the time of the pituitary stalk relapse.
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Positron emission tomography-computed tomography (PET-CT) showed marked accumulation of fluorodeoxyglucose (FDG) only in his penis (Fig. 3a). PET-CT revealed no abnormal uptake of FDG in the whole body including his penis (Fig. 3b).
Coronal sections of pituitary MR images. (a) The mass in pituitary stalk was homogeneously gadolinium-enhanced before open biopsy. (b) The mass in the pituitary stalk disappeared after whole-brain radiotherapy. Subdural liquid collection was observed around the right temporal lobe after open biopsy.
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T1-weighted images and mild homogeneous high intensity on T2-weighted images. The mass lesion was homogeneously gadolinium-enhanced (Fig. 4a). He received whole-brain radiotherapy, and MRI of the pituitary showed the disappearance of the mass (Fig. 4b).