Male pelvic squamous cell carcinoma of unknown primary origin

Abstract

Pelvic squamous cell carcinoma of unknown primary origin has been described in several case reports of female patients. However, there have been no published reports describing male patients with pelvic squamous cell cancer of unknown primary origin. Our case describes a 52-year-old man who presented with right buttock pain, rectal urgency, and constipation. His physical examination demonstrated tenderness to palpation around his gluteal folds. Computed tomography scan of his abdomen and pelvis demonstrated a large mass in his retroperitoneum. The mass was determined to be squamous cell carcinoma of unknown primary origin. Additionally, the patient had small nodules in his right lower lung lobe and right hepatic lobe. The patient was treated with concomitant chemoradiation, including cisplatin and intensity-modulated radiation therapy, followed by carboplatin and paclitaxel. The patient achieved partial remission, in which he remained one year after his presentation. Our case is consistent with the literature which suggests that squamous cell carcinoma of unknown primary origin occurring outside of the head and neck region may have a more favorable prognosis than other carcinomas of unknown primary origin. Further studies are necessary to determine the most appropriate work-up, diagnosis, and optimal treatment strategies.

Figure 1

Contrast-enhanced CT scan of the pelvis demonstrates a 6.5 × 5.1 cm mass within the right pelvis (arrows), bordered by the right obturator internus, right seminal vesicles, and bladder diverticulum. The epicenter of the mass is centered at the internal iliac neurovascular bundle.

Figure 2

Hematoxylin and eosin (H&E) stain at 100x, 200x, and 400x power, respectively, demonstrates metastatic squamous cell carcinoma. At 400x power (c), intracellular bridges (yellow arrows) and eosinophilic, intracytoplasmic keratin (black arrow) are seen, indicating squamous differentiation.

Figure 3

P63 immunostain shows positive nuclear staining in tumor cells ((a), (b)), as well as cytoplasmic staining (b), supporting the diagnosis of squamous cell carcinoma.

Figure 4

Contrast-enhanced CT scan of the pelvis demonstrates a 3.4 × 1.7 cm pelvic lesion (arrows) with no substantial soft-tissue component. The lesion is linear and elongated and appears to be comprised mainly of necrotic tissue, consistent with postradiation changes.