Primary urethral squamous cell carcinoma: a unique manifestation of a penile tumor

Abstract

This case report describes a unique manifestation of a primary urethral squamous cell carcinoma (SCC) as the underlying pathology in an 80-year-old male patient who underwent partial penectomy due to an enlarging penile mass. Persistent pain in the right knee was discovered to be a pathologic fracture using magnetic resonance imaging. Computed tomography-guided biopsy confirmed metastatic SCC. Whole-body positron emission tomography revealed systemic dissemination to multiple sites. Orthopedic knee replacement was performed in combination with local radiotherapy. Palliative chemotherapy was rejected due to poor performance status. Primary urethral SCC is rare and an uncommon cause of advanced penile cancer. These findings could be of great interest to clinicians for two reasons. First, a tumor's appearance can be misleading. Consequently, histological work-up in accordance with clinical guidelines is necessary for accurate diagnosis. Second, a more comprehensive investigation is required when clinical symptoms persist despite the use of conventional treatment. Our case is an instance in which persistent pain masked the presence of downstream metastasis. We believe that these aforementioned points are of significant clinical importance and present a salient learning opportunity.

Keywords: Penile tumor; computed tomography; magnetic resonance imaging; metastasis; positron emission tomography; primary urethral squamous cell carcinoma.

Figure 1.

a: Plain film radiographs (anterior posterior view) of the right knee demonstrating no obvious pathology. b: Coronary T1-weighted magnetic resonance imaging of the right knee showing extensive metastasis with cortical infiltration and a fracture line of the medial femur condyle (arrows). c: Whole-body positron emission tomography scan displaying dissemination to multiple sites: bilateral inguinal lymph nodes, right femur, right fibula, right tibia, and right fourth metatarsal bone.

Figure 2.

Representative microscopic images of primary urethral squamous cell carcinoma and femoral bone metastasis using hematoxylin and eosin staining. a: Partial penectomy specimen – overview with squamous cell carcinoma (original magnification, OM). b: Partial penectomy specimen with blood vessel invasion of squamous cell carcinoma (10× OM). c: Partial penectomy specimen with squamous cell carcinoma in situ (left side) and penile invasion (right side) (10× OM). d: Core bone biopsy overview with metastasis (arrow) of the right femoral bone (OM). e: Femoral bone metastasis with cortical involvement (2× OM). f: Femoral bone metastasis with focal spindle cell-like morphology (20× OM).