case_images: PMC11721210_01
case_images: T1-weighted MRI pelvis. Sagittal view. A mass measuring 22mm x 16mm is identified in an intimate relationship to the inferior posterior urethra and the anterior vaginal wall. No enlarged pelvic nodes or groin nodules. This mass is concerning for malignancy.
case_images: gr1.jpg
case_images: PMC11721210_01_gr1.jpg
case_images: fig1
case_images: The MRI Pelvis confirmed the presence of a 22mm solid urethral meatus tumour of unknown aetiology (Fig. 1), and a decision was made to excise the lesion and reconstruct the urethra.
case_images: Malignant melanoma in situ. a) Urethral mucosa with an irregular nested proliferation of atypical melanocytes demonstrating mucosal melanoma in situ (H&E x 100). b) Urethral mucosa with an irregular nested proliferation of atypical melanocytes at the base with upward (pagetoid) extension of abnormal melanocytes, demonstrating mucosal melanoma in situ (H&E x 200). c) Cellular detail from a nodule of invasive malignant melanoma demonstrating discohesive malignant melanocytes with brisk mitotic activity and atypical mitoses (H&E x 400).
case_images: gr2.jpg
case_images: PMC11721210_01_gr2.jpg
case_images: fig2
case_images: The lesion was successfully excised in the same manner as excision of urethral caruncle and histology revealed B-RAF negative malignant melanoma (Fig. 2a-c) with positive surgical margins.
case_images: Whole body PET-CT. PET-CT performed post-operatively. FDG uptake around the resection site of the mid-urethra. This is consistent with residual disease/positive margins, extending over 20mm.
case_images: gr3.jpg
case_images: PMC11721210_01_gr3.jpg
case_images: fig3
case_images: In view of this histology, Positron Emission Tomography/CT (PET/CT) was arranged and confirmed FDG uptake at the mid urethra at the excision site (extending over 20mm) (Fig. 3) but nowhere else in the body.