S1764 Three Undiagnosed Primary Malignancies Presenting as Chronic Diarrhea

Abstract

INTRODUCTION: Clinicians are taught to differentiate the symptoms of unintentional weight loss, decreased appetite and night sweats to include malignancies in their differentials. When these clues are absent or replaced with seemingly unrelated symptoms, the diagnosis of malignancy is often delayed. We present a case of chronic diarrhea, neurologic symptoms and urinary retention found to be secondary to three undiagnosed primary malignancies. CASE DESCRIPTION/METHODS: A 68 year old man with unremarkable past medical history transferred to Honolulu from the Philippines after extended hospitalization. He presented with 3 months of chronic watery diarrhea, 30 lbs weight loss, progressive weakness of all extremities, peripheral neuropathy, and unexplained urinary retention. While hospitalized in the Philippines a Foley catheter was placed. He was also informed that his bladder wall was thickened. Arriving at Tripler Army Medical Center, preliminary tests evaluating chronic diarrhea were unremarkable. CT abdomen and pelvis was significant for diffuse bladder wall thickening and previously unknown abdominal mass in the lesser sac. Bladder biopsy showed papillary bladder tumor which was transitional cell carcinoma. Investigation of the abdominal mass via endoscopy revealed moderately differentiated gastric adenocarcinoma (HER2neu+). Given his persistent extremity weakness and muscle wasting, MRI of the spine and brain was obtained which demonstrated diffuse signal abnormalities in the thoracic and lumbar spine. PET scan revealed 5.2 cm hypermetabolic pararectal mass and transrectal ultrasound biopsy diagnosed a gastrointestinal stromal tumor (GIST). Initial treatment plan included trastuzumab and surgery, therefore screening echocardiogram was obtained. Unfortunately, this revealed significant infiltrative cardiomyopathy with severely reduced ejection fraction. Thus, the patient was no longer deemed a good treatment candidate. Given poor prognosis, he declined further diagnostic workup and transitioned to comfort care. DISCUSSION: This case is the first instance in literature of these three primary cancers presenting in one patient. Tumors in the pararectal area account for only 5% of all GIST presentations, and presence of two additional primary cancers makes this rare presentation even more unique. Diffuse signal abnormalities in spine along with his infiltrative cardiomyopathy also raised suspicion for multiple myeloma, however as the patient transitioned to comfort care, any further investigation was precluded.Figure 1.: Gastric Adenocarcinoma: Dysplastic glands overlying invasive moderately differentiated adenocarcinoma.Figure 2.: Pararectal Gastrointestinal Stromal Tumor: Cell block section showing clusters of atypical cells with abundant delicate eosinophilic cytoplasm. Nuclei are enlarged, appear round to oval with smooth nuclear contours, and display a mild to moderate degree of pleomorphism 40x.Figure 3.: Pararectal Gastrointestinal Stromal Tumor: Positive Immunohistochemical Staining DOG-1 (20x) (Specific for GIST).