Harper, Eugene P.

Abstract Background Echinococcus multilocularis is a destructive zoonotic cestode with low human incidence. Hydatid disease classically presents with hepatic or lung involvement with infrequent extrahepatic bone destruction. Diagnosis is challenging due to its latency and mimicry. Fig.1: Case 1 - X-ray imaging of the pelvis shows osseous destruction of the iliac crest secondary to known osteomyelitis status post left ilium debridement. Fig.2: Case 1 - Magnetic resonance imaging demonstrates extensive osteomyelitis throughout left ilium. Stable scattered focal fluid collections seen throughout the left lower quadrant. Methods CASE 1: A 57 year-old Albanian male with diabetes, latent TB, and left iliac lytic lesion presented with 4 weeks of left flank pain and was treated with 6 weeks of IV Ceftriaxone and Flagyl. 2 years later he returned with flank pain and purulent lumbar drainage. Hip x-ray suggested chronic osteomyelitis, with left psoas fluid collections on CT. Bartonella, Q fever, Brucella, HIV, AFB and fungal serologies were negative. Hemipelvis debridement revealed structures concerning for hydatid disease. Echinococcus IgG was equivocal. Histopathology was consistent with Echinococcus multilocularis species, and albendazole was started. On follow-up, he presented with left hip tenderness and toe extensor weakness. Labs showed mild leukocytosis. CT revealed progressive destruction of the left iliac with sacroiliac extension concerning for abscess. CASE 2: A 36 year-old female presented with lung and liver cysts, progressive dyspnea, and non-productive cough. She lived in Africa, Asia, and Europe and consumed local street food and unpasteurized milk. Hobbies included spelunking and swimming in freshwater lakes. She had exposure to stray animals, but denied bites or scratches. Over 4 years dyspnea progressed to orthopnea. MR abdomen revealed a 10x6x12cm liver cyst and chest CT showed 2 fluid-attenuating lesions in the LLL and RLL, measuring 4.9 x 6.0 cm and 6.8 x 4.3 cm respectively. Echinococcus, Bartonella, Q fever, Brucella, HIV, AFB and fungal serologies were negative. Schistosomiasis serology was equivocal. Fig. 3: Case 2 - MRI abdomen demonstrating 10x6x12cm liver cyst Fig. 4: Case 2 - Chest CT showed 2 dominant fluid attenuating lesions within the LLL and RLL. The larger lesion in RLL measures 6.8 x 4.3 cm. The left lower lobe lesion measures 4.9 x 6.0 cm. Results Patient 1 underwent type I hemipelvectomy. Patient 2 underwent pulmonary segmentectomy and liver lobectomy. Both were continued on albendazole. Fig. 5: Case 1 - Photo taken during debridement of left ileac and hip. Note presence of white cysts discovered intraoperatively. Fig. 6: Case 1 - Histopathologic slides (H&E stain) demonstrating hooks and scolices consistent with Echinococcus multilocularis. A. Hooklet (100x magnification). B. Hydatid cyst with black-staining structures suggestive of degenerating hooklets. C. Zoomed detail of cyst wall. D. Degenerating hydatid cyst and hooklets. Conclusion Equivocal IgG serology does not exclude infection. History and clinical presentation are key to diagnosis, but histopathology remains the gold standard. Hydatid bone infection progresses insidiously and frequently recurs, depending upon excision and debridement. Finally, echinococcosis demands aggressive long-term therapy and surveillance. Disclosures Claudia R. Libertin, MD, Pfizer, Inc. (Grant/Research Support, Research Grant or Support)

Goals: Our aim was to develop a scoring system to predict risk of microscopic colitis (MC), to identify patients at low risk, potentially avoiding unnecessary biopsies. Background: Patients with chronic diarrhea often undergo colonoscopy with biopsy, but few have histologic abnormalities. Study: We conducted a retrospective study of patients with chronic diarrhea and a macroscopically normal colonoscopy at our institution over a 9-month period. Multivariable logistic regression assessed the association between predictors and the presence of biopsy-proven MC. Results: The derivation cohort included 617 patients. Median age was 55.1 (39.6 to 68.1) years; 397 (64.3%) were female and 81 (13.1%) had MC. Age ≥55 years, duration of diarrhea ≤6 months, ≥5 bowel movements per day, body mass index <30 kg/m2, current smoking, and current use of selective serotonin reuptake inhibitors/serotonin-norepinephrine reuptake inhibitorss and non-steroidal anti-inflammatory drugs were independently associated with MC. A score of ≥10 points in our scoring system, yielded an area under the ROC curve (AUC) of 0.83 with a sensitivity of 93% and specificity of 49% in predicting which patients have MC. The negative predictive value (NPV) was 97.8% (95.0% to 99.1%). In the validation cohort, the scoring system performed similarly (AUC 0.79, sensitivity 91%, specificity 49%, NPV 97%). By avoiding biopsies in patients at low risk of having MC, costs associated with colon biopsies could be reduced by almost 43%. Conclusion: This scoring system including 7 clinical variables was able to identify patients unlikely to have MC, with excellent sensitivity, reasonable specificity, and a high NPV, translating into important potential cost savings.