About the Program
Next opening: 2027-2028
Number of positions: 1
Length: 1 year
This ACGME-accredited fellowship provides robust training in disorders of the luminal GI tract, pancreas and hepatic pathology (medical liver including liver transplantation), preparing trainees for a career in an academic or private practice setting. Five GI pathologists provide clinical service, contribute to the research program of the GI section, and support the GI Pathology training program across four distinct hospital and outpatient settings.
The GI pathology fellow will get exposure to a comprehensive spectrum of gastrointestinal surgical specimens, ranging from small biopsies to complex procedures, as well as hepatobiliary specimens. Training also includes reviewing consult digital slides from community practices in Texas. The fellow will have graduated responsibility in performing operating room consultations (frozen sections and gross examination). The fellow is expected to closely interact with surgeons/clinicians and pathology colleagues from community practice, actively participate in tumor boards, IBD/liver conferences, participate in research projects and will have the opportunity to attend and contribute to numerous didactic and clinical conferences.
Rotations
The fellow will rotate across two institutions: Baylor St. Luke’s Medical Center and Texas Children’s Hospital, with a one-month rotation at MD Anderson Cancer Center. Program strengths include extensive experience in routine and complex gastrointestinal pathology, pancreatic pathology, medical liver biopsies, liver transplantation, and pediatric pathology.
A one-week rotation in clinical gastroenterology is included, during which the fellow may observe advanced endoscopic procedures such as EMR/ESD and EUS-guided FNA/FNB performed by experienced gastroenterologists.
Stipends and Benefits
Visit the Graduate School of Biomedical Sciences page on stipends and benefits for fellows.
Admissions
Candidates must be board certified or eligible for certification in anatomic pathology or AP/CP.
All application materials, including recommendation letters, must be submitted online, and include the following:
- Completed online House Staff Application
- Current Curriculum Vitae
- Personal Statement
- Transcript from Medical School(s)
- Three Recommendation Letters
Applications are accepted from mid-April to July 31 for positions beginning July 1 two years later. Interviews are conducted starting in July or August and are completed by the end of August of the application year.
Case of the Month
Case history: 57-year-old man with a history of ulcerative proctitis and intermittent rectal bleeding underwent screening colonoscopy.
Colonoscopy: Unremarkable without evidence of active inflammation or mucosal abnormalities.
Pathology: Histological examination of terminal ileal biopsies demonstrated patchy thickening of subepithelial collagen, consistent with Collagenous Ileitis. A Masson Trichrome stain highlighted the increased subepithelial collagen deposition, supporting the diagnosis of collagenous ileitis.
Question:
A 60-year-old woman undergoes ileocolonoscopy for evaluation of chronic watery diarrhea. The terminal ileum appears grossly unremarkable. Biopsies of the terminal ileum reveal a thickened, irregular subepithelial collagen band measuring 40 μm with entrapped capillaries and inflammatory cells. Which of the following is the most appropriate next step in the evaluation of this patient?
A. Initiation of budesonide therapy
B. Serologic testing for anti-tissue transglutaminase antibodies
C. Biopsy sampling from additional gastrointestinal sites to evaluate for multifocal collagenous disease
D. Repeat ileoscopy in 6 months with surveillance biopsies
E. CT enterography to exclude Crohn disease
Correct Answer: C
Explanation: The histologic findings are diagnostic of collagenous ileitis. Because collagenous ileitis may occur as part of a generalized collagenous mucosal disease, with concurrent collagenous colitis and collagenous gastritis found in a substantial proportion of cases, biopsy sampling from multiple gastrointestinal sites (colon, stomach, and duodenum) should be considered to evaluate for multifocal involvement. While budesonide (A) may ultimately be used for treatment, establishing the full extent of disease is an important initial step. Serologic testing for celiac disease (B) may be reasonable in the workup of chronic diarrhea but does not address the key management consideration specific to a new diagnosis of collagenous ileitis.
Discussion: Collagenous ileitis (CI) is a rare entity within the spectrum of collagenous mucosal inflammatory diseases of the gastrointestinal tract, which also includes collagenous colitis, collagenous gastritis, and collagenous sprue. It is defined by the presence of a thickened subepithelial collagen band in the terminal ileal mucosa and remains poorly characterized, with fewer than 15 cases reported in the literature to date.
Clinically, CI predominantly affects middle-aged elderly adults and presents most commonly with chronic, watery, non-bloody diarrhea. The endoscopic appearance of the terminal ileum is typically unremarkable. The defining histopathologic feature is a thickened, irregular subepithelial collagen band, ranging from 15 to over 100 μm, with a jagged deep border that may entrap capillaries, red blood cells, and inflammatory cells. In equivocal cases, connective tissue stains such as Masson trichrome or tenascin immunohistochemistry may aid in highlighting the collagen band.
CI may occur as an isolated ileal process or as part of a generalized collagenous mucosal disease involving the colon, stomach, and duodenum. Concurrent collagenous colitis and collagenous gastritis are found in a substantial proportion of cases, supporting the recommendation that when CI is identified, biopsy sampling from multiple gastrointestinal sites should be considered to evaluate for multifocal involvement.
The pathogenesis is not fully understood but is believed to involve immune-mediated myofibroblast activation leading to excessive deposition of interstitial collagens and tenascin in the subepithelial zone, coupled with impaired matrix degradation. As with collagenous colitis, both autoimmune associations and medication exposure appear to play important etiologic roles. An expanding list of medications has been implicated in triggering collagenous mucosal disease, including NSAIDs, proton pump inhibitors, SSRIs/SNRIs, and immunosuppressive agents such as mycophenolate mofetil. Recognition of drug-induced CI is clinically important because withdrawal of the offending agent may lead to complete symptomatic and histologic resolution.
The differential diagnosis of subepithelial collagen thickening in the ileum includes collagenous sprue extending distally, celiac disease with secondary collagen deposition, ischemic injury, and drug-induced enteropathy. Collagenous sprue is distinguished by its predominant involvement of the proximal small bowel with prominent villous atrophy, and has been increasingly linked to medication exposure, particularly angiotensin II receptor blockers.
No treatment trials are specific to collagenous ileitis. Management is largely extrapolated from collagenous colitis, with budesonide commonly used despite frequent relapse after discontinuation. Withdrawal of potential offending medications is an important first step and may be sufficient, with most reported cases showing clinical improvement and occasional histologic resolution.
References:
1. O'Brien BH, McClymont K, Brown I. Collagenous ileitis: a study of 13 cases. Am J Surg Pathol. 2011;35(8):1151-1157. doi:10.1097/PAS.0b013e3182206ef5
2. Freeman HJ. Collagenous mucosal inflammatory diseases of the gastrointestinal tract. Gastroenterology. 2005;129(1):338-350. doi:10.1053/j.gastro.2005.05.020
3. Langner C, Aust D, Ensari A, Villanacci V, Becheanu G, Miehlke S, Geboes K & Münch A; on behalf of the Working Group of Digestive Diseases of the European Society of Pathology (ESP) and the European Microscopic Colitis Group (EMCG) (2015) Histopathology66, 658–663. Histology of microscopic colitis—review with a practical approach for pathologists DOI: 10.1111/his.12592
4. Wang B, Xi W, Li H. Mycophenolate mofetil-associated collagenous ileitis in a kidney transplant recipient: A case report. Clin Nephrol. 2023;99(5):256-259. doi:10.5414/CN111055
5. Parfitt JR, Jayakumar S, Driman DK. Mycophenolate mofetil-related gastrointestinal mucosal injury: variable injury patterns, including graft-versus-host disease-like changes. Am J Surg Pathol. 2008;32(9):1367-1372. doi:10.1097/pas.0b013e31816bf3fe
6. Miehlke S, Verhaegh B, Tontini GE, Madisch A, Langner C, Münch A. Microscopic colitis: pathophysiology and clinical management. Lancet Gastroenterol Hepatol. 2019;4(4):305-314. doi:10.1016/S2468-1253(19)30048-2
7. Günther U, Schuppan D, Bauer M, et al. Fibrogenesis and fibrolysis in collagenous colitis. Patterns of procollagen types I and IV, matrix-metalloproteinase-1 and -13, and TIMP-1 gene expression. Am J Pathol. 1999;155(2):493-503. doi:10.1016/S0002-9440(10)65145-0