Urachal mixed adenocarcinoma and small cell neuroendocrine carcinoma with widespread metastasis and resistance to chemotherapy: a case report

Abstract

Neuroendocrine carcinoma arising from the urachus is extremely rare. We describe a case of a 33-year-old gentleman who presented with hematuria and diagnosed to have a composite adenocarcinoma and small cell neuroendocrine carcinoma arising from the urachus. The patient also had widespread metastasis at the time of presentation, therefore, he was referred for chemotherapy. However, the disease showed progression despite treatment. Recognition of neuroendocrine carcinoma component in urachal tumors, although rare, is very essential as this histologic type carries poor prognosis with aggressive clinical outcome.

Keywords: Adenocarcinoma; Chemotherapy; Metastasis; Small cell neuroendocrine carcinoma; Urachus.

Fig. 1

Microscopic features of the tumor. A, photomicrograph depicting a tumor located deep in the bladder wall with sharp demarcation from the surface urothelium (Hematoxylin & Eosin stain, × 40). B, the adenocarcinoma component of enteric type with extracellular mucin (Hematoxylin & Eosin stain, × 200). C, the adenocarcinoma component of signet ring type with intracellular mucin (Hematoxylin & Eosin stain, × 200). D, the small cell neuroendocrine carcinoma component with confluent areas of necrosis in the center (Hematoxylin & Eosin stain, × 200). E, High-power view of the small cell neuroendocrine carcinoma component with brisk mitosis and apoptosis (Hematoxylin & Eosin stain, × 400)

Fig. 2

Morphology of tumor with contrasting immunostaining. A, Photomicrograph showing adenocarcinoma component with signet ring cells (right) and neuroendocrine carcinoma component (left) (Hematoxylin & Eosin stain, × 200). B, positive nuclear staining for CDX2 in the adenocarcinoma component (right) while it’s negative in the neuroendocrine carcinoma component (left). C, the small cell neuroendocrine carcinoma component (left) is diffusely and strongly positive for synaptophysin while the adenocarcinoma component (right) is negative

Fig. 3

Staging (left column) and restaging (right column) FDG PET/CT scan maximum intensity projection (MIP—A-B) and fused sagittal (C-D and I-J), coronal (E–F) and transaxial (G-H) images. The primary tumor in the ventral aspect of the urinary bladder (red arrowhead) was seen even with the presence of the excreted FDG in the bladder. Bilateral parailiac lymph nodes showed progression during treatment (blue arrowheads). Liver metastasis in the left lobe has also increased in size (green arrowhead). Irradiated D5 vertebral body lesion partially responded (yellow arrowhead). Physiologic brown fat activity was noted on the staging scan (brown arrowheads)