ADENOSQUAMOUS CARCINOMA: AN ABNORMAL PRESENTATION OF A RARE MALIGNANCY X Diaz-Hernandez MD, C Wexler MD, SK Aggarwal MD. Louisiana State University Health Sciences Center, Lafayette, LA
INTRODUCTION Adenosquamous cell carcinoma of the intestine is a rare and aggressive malignancy. Carcinoma-adenosquamous cell carcinoma (Ad-SCC) histogenesis is poorly understood as it is an exceedingly rare colon cancer characterized by two histopathologies (both glandular and squamous features).
CASE: A 22-year-old man presented with right upper quadrant (RUQ) abdominal pain and hematochezia for two months. The patient reported associated anorexia with 30-pound weight loss. Labs revealed elevated AST (52), ALT (79), and ALP (197), normal bilirubin, anemia (Hb 11.8). On physical exam, RUQ tenderness to deep palpation and left supraclavicular and cervical lymphadenopathy was noted. Computed tomography of the abdomen revealed thickening of the colon splenic flexure suspicious for infiltrative neoplasm, bilobar hepatic metastasis and diffuse abdominal and pelvic lymphadenopathy. Colonoscopy revealed large, infiltrative, friable mass of the proximal descending colon and splenic flexure with 50% involvement of luminal circumference. Biopsies were consistent with poorly differentiated Ad-SCC of the intestine with composite type. DISCUSSION: Ad-SCC two histopathologies (both glandular and squamous features) are mixed tumors classified into 2 subgroups: composite vs collision-type. The composite type consists of both histopathologies within a single tumor. The collision type consists of 2 tumors “side-by-side, one with each histopathology. Ad-SCC has a worse prognosis than adenocarcinoma and is more likely to present with metastasis versus adenocarcinoma (46% vs 42% respectively). Metastasis is typically more common at presentation. Ad-SCC has a lower 5-year survival rate (31% vs 66% respectively) with distant metastasis being associated with poorer outcomes. Definitive treatment consists of surgical resection to remove the entire tumor. Limited data regarding the role of adjuvant chemotherapy and radiation is available as this is a rare malignancy and evidence is lacking to support an appropriate regimen.
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