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Perianal pathology beyond fistulizing disease: spectrum of MRI findings and diagnostic pitfalls
1Department of Radiology, Basurto University Hospital, Bilbao, Spain. feanim2000@yahoo.es.
Abstract:
Magnetic resonance imaging (MRI) of the perianal region is frequently performed in the context of fistulizing disease; however, a broad spectrum of non-fistulizing conditions may also affect this region. A wide variety of inflammatory, infectious, vascular, cystic, and neoplastic conditions, as well as anatomical variants and post-surgical changes, may involve the perianal region and often present with overlapping or nonspecific clinical manifestations.MRI, owing to its superior soft tissue contrast and multiplanar capability, plays a central role in the evaluation of perianal pathology. Beyond lesion detection, MRI enables accurate characterization, assessment of disease extent, and differentiation between entities that may be clinically indistinguishable, thereby supporting appropriate therapeutic decision-making. Importantly, perianal abnormalities may also be incidentally detected on pelvic MRI studies performed for unrelated indications. In such cases, unfamiliarity with the full spectrum of perianal findings may represent a source of diagnostic uncertainty, particularly for less experienced radiologists.This review focuses on the MRI appearance of non-fistulizing perianal pathology, emphasizing key imaging features that aid in differential diagnosis across a broad range of benign and malignant conditions. Representative cases from routine clinical practice are presented to illustrate typical and atypical imaging patterns, as well as common diagnostic pitfalls. Selected complementary computed tomography findings are included when relevant.Given the relative infrequency of many perianal conditions, comprehensive knowledge of their MRI features, along with recognition of normal anatomical variants and expected post-treatment appearances, is essential. Such familiarity helps avoid misinterpretation, unnecessary invasive procedures, and delayed diagnosis, ultimately contributing to improved patient management and clinical outcomes.
Insights
Magnetic resonance imaging (MRI) is crucial for diagnosing diverse non-fistulizing perianal conditions. Understanding key MRI features aids radiologists in differentiating various pathologies, improving patient management.
Area of Science:
- Radiology
- Gastroenterology
- Oncology
Background:
- Perianal region MRI is common for fistulizing disease, but non-fistulizing conditions also present.
- Diverse pathologies like inflammatory, infectious, cystic, and neoplastic conditions affect the perianal region, often with overlapping symptoms.
- Incidental perianal findings on pelvic MRI can cause diagnostic uncertainty for less experienced radiologists.
Purpose of the Study:
- To review the MRI appearance of non-fistulizing perianal pathology.
- To highlight key imaging features for differential diagnosis of benign and malignant conditions.
- To aid radiologists in interpreting incidental perianal findings.
Main Methods:
- Review of MRI features of non-fistulizing perianal conditions.
- Presentation of representative cases with typical and atypical imaging patterns.
- Inclusion of complementary computed tomography findings where relevant.
Main Results:
- MRI offers superior soft tissue contrast and multiplanar capabilities for perianal pathology evaluation.
- Accurate characterization and assessment of disease extent are enabled by MRI.
- Key imaging features are emphasized to differentiate various benign and malignant perianal conditions.
Conclusions:
- Comprehensive knowledge of MRI features for perianal conditions is essential for accurate diagnosis.
- Familiarity with normal variants and post-treatment appearances prevents misinterpretation and delayed diagnosis.
- Improved radiologist understanding of perianal MRI findings contributes to better patient outcomes.
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