Update on Pathologic Conditions, Imaging Findings, Prevention, and Management of Human Papillomavirus-related Neoplasms

Human papillomavirus (HPV) is the most common sexually transmitted infection that proliferates in the squamous epithelium and is the most common source of viral-related neoplasms. Low-risk subtypes (HPV-6 and -11) cause respiratory papillomas (laryngeal, tracheal, and bronchial) and condyloma acuminata of the penis, anus, and perineal region (anogenital warts). High-risk subtypes (HPV-16, -18, -31, and -33) are responsible for oropharyngeal squamous cell carcinoma (SCC) that involves the tongue base, tonsils, posterior pharyngeal wall, and larynx and malignancies of the anogenital region (cancers of the cervix, vagina, vulva, penis, and anal canal). Recent studies have increasingly shown a favorable treatment response and substantial differences in the overall prognosis associated with HPV-associated oropharyngeal cancers. Given this fact, oropharyngeal, cervical, and penile SCCs are classified as HPV-associated and HPV-independent cancers in the current World Health Organization classification. Imaging is essential in the early detection, diagnosis, and staging of HPV-associated cancers. Imaging also helps assess treatment response and postoperative complications and is used for long-term surveillance. HPV-associated oropharyngeal SCCs have well-defined borders and solid and cystic nodal metastases at imaging. Updated screening and vaccination guidelines are currently available that have great potential to decrease the overall disease burden and help control this worldwide public health concern. Novel therapeutic strategies, such as immunotherapies, are being explored, and imaging biomarkers that can predict treatment response and prognosis are being investigated; radiologists play a pivotal role in these efforts. ©RSNA, 2024 Supplemental material is available for this article.

From benign to malignant: unveiling invasive squamous cell carcinoma following resection of perianal condyloma acuminatum: a case report

This case illustrates the surgical management of a perianal mass, initially misdiagnosed as condyloma acuminatum in a male patient in his late 50s, later identified as invasive squamous cell carcinoma following excision. Despite extensive preoperative evaluation, the lesion's malignancy was confirmed through histopathology. The significant, fungating mass required a multidisciplinary approach, culminating in a pT3 staging and additional wide excision with inferior gluteal artery perforator flap reconstruction. This case underscores the critical importance of surgical diligence and adaptability, highlighting the role of comprehensive surgery in both diagnosis and treatment of complex perianal malignancies, and reaffirms the value of a multidisciplinary team in achieving favourable outcomes.

Low Rectal Cancers at Initial Staging MRI

Low rectal cancers, which are associated with increased risk of local recurrent disease and poorer prognosis, have unique anatomic considerations and issues for staging and treatment that do not apply to mid and high rectal cancers. Although tumor histology help drive the staging and treatment of all rectal cancers, it is of particular importance in low rectal cancers, which may involve the anal canal, to help establish whether a low rectal mass should be staged and treated as a rectal cancer (ie, adenocarcinoma) or an anal cancer (ie, squamous cell carcinoma). Optimal staging and treatment of rectal cancer are contingent on tumor location and local extent, which help guide management decisions including neoadjuvant therapy and curative surgical treatment strategies. Tumor location in the low rectum and local involvement of the anal canal, sphincter, and pelvic floor help determine whether a patient can undergo sphincter-preserving resection such as a low anterior resection versus abdominoperineal resection to achieve negative surgical margins. Issues exist related to the anatomy and patterns of disease spread that are unique to the low rectum and include how to determine and stage anal sphincter involvement, mesorectal fascia status at the pelvic floor, and nodal status of extramesorectal nodes such as the external iliac and inguinal lymph nodes. For these reasons, it is imperative that radiologists who interpret rectal cancer staging MRI examinations feel comfortable with the unique anatomy of the low rectum and anal canal, nuances of low rectal cancer local disease spread, and treatment paradigms for low rectal cancer. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Gollub in this issue.

Beyond squamous cell carcinoma: MRI appearance of uncommon anal neoplasms and mimickers

Anal cancer is an uncommon malignancy. In addition to squamous cell carcinoma, there are a variety of other less common malignancies and benign pathologies that may afflict the anal canal, with which abdominal radiologists should be familiar. Abdominal radiologists should be familiar with the imaging features that can help distinguish different rare anal tumors beyond squamous cell carcinoma and that can aid in diagnosis therefore help steer management. This review discusses these uncommon pathologies with a focus on their imaging appearance, management, and prognosis.

Role of MRI special diffusion weighted imaging/diffusion tensor imaging techniques in the assessment of perianal fistula activity

Background

Pre-operative MRI examination is currently considered as an evolving tool for assessment of perianal fistula types, extensions, and complications to achieve proper treatment plan. Proper assessment of fistula activity can also have a major contributing role to the treatment plan, through deciding the type of prescribed medications, proper surgical approach as well as the proper operative intervention timing. Reviewing literature, only few studies have mentioned the importance of diffusion tensor imaging (DTI) sequences in diagnosing perianal fistula activity, yet many studies have discussed the perianal fistula activity assessment using other diffusion weighted imaging (DWI) sequences. In the present study, the main objective was to prove the MRI quantitative DTI sequences’ ability of diagnosing perianal fistulae inflammatory activity.

Results

This study was a prospective analysis in which fistular activity was confirmed by intra-operative findings (considered as the standard reference). The cases included in the study were divided into two groups, based on their surgical findings, positive inflammatory and negative inflammatory groups. Both groups were pre-operatively assessed using MRI imaging and additionally used diffusion weighted and tensor imaging (DWI and DTI) sequences by special post-processing quantitative assessment of DTI FA and ADC values. There was significant statistical difference between the mean ADC value of the PIA and NIA groups in the track, edema, ipsilateral and contralateral sphincter areas with P values (P = 0.000, 0.000, 0.002 and 0.000 respectively). There was also significant difference between the mean FA value of the PIA and NIA groups in the track, edema, ipsilateral and contralateral sphincter areas with P values (P = 0.000, 0.000, 0.000 and 0.008 respectively).

Conclusion

This study results revealed that FA are relatively lower in positive inflammatory activity lesions than in negative inflammatory activity lesions while the ADC values were relatively higher in positive inflammatory activity lesions than in negative inflammatory activity lesions and the differences were statistically significant having a fundamental role in the assessment of perianal fistula activity especially at the track area being of highest sensitivity and specificity. Unlike conventional MRI sequences which revealed only high specificity being a good negative modality.

A case of male perineal aggressive angiomyxoma with expressions of female hormone receptors

Introduction

Aggressive angiomyxoma is a rare mesenchymal tumor in females of reproductive age that occurs in the pelvis and perineal zone with a high risk of local infiltration and recurrence. Male aggressive angiomyxoma in perineal zone is very rare.

Case presentation

A 63‐year old male presented to our hospital with chief complaint of perineal mass. He was diagnosed with perineal lipoma by needle biopsy 3 years before. Computed tomography revealed a 16 cm perineal tumor without lymph node or distal metastasis. As the tumor had gradually increased, we performed tumor resection. The histological diagnosis of tumor using immunohistochemistry was aggressive angiomyxoma with complete resection. Moreover, expressions of both estrogen and progesterone receptors were recognized. No recurrence was seen 9 months after surgery.

Conclusion

Male aggressive angiomyxoma is a very rare tumor, which has expressions of female hormone receptors. Hormonal therapy might be effective for perioperative therapy or recurrence.

Anorectal pathology in the HIV population: a guide for radiologists

Patients with human immunodeficiency virus (HIV) can present with a wide range of different acute and chronic pathologies. Anorectal conditions are particularly common in this unique patient population, including pathologies, such as proctitis, anorectal abscess, anorectal fistula, and anal squamous cell carcinoma. The radiologist plays a critical role in the assessment of these common forms of anorectal disease, as these conditions can present with various findings on imaging assessment. Pelvic CT, MRI, and FDG-PET/CT are among the most common modalities used for assessment of anorectal disease in the HIV patient population. Knowledge of the fundamental clinical and imaging findings associated with these pathologies in HIV patients is critical for radiologists.

Gastrointestinal Manifestations of Immunodeficiency: Imaging Spectrum

There is a wide spectrum of hereditary and acquired immunodeficiency disorders that are characterized by specific abnormalities involving a plethora of humoral, cellular, and phagocytic immunologic pathways. These include distinctive primary immunodeficiency syndromes due to characteristic genetic defects and secondary immunodeficiency syndromes, such as AIDS from HIV infection and therapy-related immunosuppression in patients with cancers or a solid organ or stem cell transplant. The gut mucosa and gut-associated lymphoid tissue (the largest lymphoid organ in the body), along with diverse commensal microbiota, play complex and critical roles in development and modulation of the immune system. Thus, myriad gastrointestinal (GI) symptoms are common in immunocompromised patients and may be due to inflammatory conditions (graft versus host disease, neutropenic enterocolitis, or HIV-related proctocolitis), opportunistic infections (viral, bacterial, fungal, or protozoal), or malignancies (Kaposi sarcoma, lymphoma, posttransplant lymphoproliferative disorder, or anal cancer). GI tract involvement in immunodeficient patients contributes to significant morbidity and mortality. Along with endoscopy and histopathologic evaluation, imaging plays an integral role in detection, localization, characterization, and distinction of GI tract manifestations of various immunodeficiency syndromes and their complications. Select disorders demonstrate characteristic findings at fluoroscopy, CT, US, and MRI that permit timely and accurate diagnosis. While neutropenic enterocolitis affects the terminal ileum and right colon and occurs in patients receiving chemotherapy for hematologic malignancies, Kaposi sarcoma commonly manifests as bull's-eye lesions in the stomach and duodenum. Imaging is invaluable in treatment follow-up and long-term surveillance as well. Online supplemental material is available for this article. ^©RSNA, 2022.

Perianal Inflammation or Something More?

Perianal fistulae are commonly complicated by abscesses and ramifications, which have well-recognized imaging morphology. Less commonly, atypical findings of solid enhancing mass-like lesions with no fluid component are associated with chronic and recurrent fistulae, the etiology of which includes inflammatory masses as well as locally aggressive malignancy. The latter predicts poorer prognosis and warrants extensive surgical resection. The reading radiologist must identify the unusual appearance, be aware of the possible etiologies, and if appropriate recommend prompt tissue sampling to exclude malignancy. This is pertinent as it determines surgical management, which is crucial in achieving a potential curative outcome.

Second Malignancies after Radiation Therapy: Update on Pathogenesis and Cross-sectional Imaging Findings

A wide spectrum of second cancers occur as late complications of radiation therapy (RT) used to treat various malignancies. In addition to the type and dose of radiation, lifestyle, environmental, and genetic factors are important to the development of second malignancies in cancer survivors. Typically, RT-induced malignancies (RTIMs) are biologically aggressive cancers with a variable period of 5-10 years for hematologic malignancies and 10-60 years for solid tumors between RT and the development of the second cancer. Although carcinomas and leukemias commonly develop after low-dose RT, sarcomas occur in tissues or organs that receive high-dose RT. Angiosarcomas and unclassified pleomorphic sarcomas are the two most common RT-associated sarcomas; other sarcomas include malignant peripheral nerve sheath tumors, leiomyosarcomas, osteosarcomas, chondrosarcomas, and dedifferentiated or pleomorphic liposarcomas. Select RTIMs show tumor genetic characteristics that allow accurate diagnosis. Nearly all cutaneous angiosarcomas after RT for breast cancer and 90% of RT-associated malignant peripheral nerve sheath tumors are characterized by MYC gene amplifications and loss of H3 K27me3 expression, respectively. Classic papillary thyroid carcinomas that develop after RT frequently harbor RET/PTC rearrangements and have a favorable prognosis, despite their advanced stage at patient presentation. Select RTIMs demonstrate characteristic imaging findings and typically develop in the prior radiation field. Imaging is essential to early diagnosis, characterization, localization, and staging of RTIMs. Familiarity of radiologists with the diverse spectrum of RTIMs is essential for early diagnosis and optimal management. An invited commentary by Shapiro is available online. ^©RSNA, 2021.

Perianal squamous cell carcinoma: A case report

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Perianal squamous malignancies are often misdiagnosed leading to delay in treatment.

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Surgical management aims to preserve sphincter function.

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Chemoradiation is preferred in cases of suspected sphincter involvement.

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Some superficial muscle fibers may be resected in select cases without loss of function.

Introduction and importance

Perianal carcinomas, though rare, are usually squamous cell carcinoma. Current literature recommends surgical excision for tumors staged T1-T2, N0 without external anal sphincter involvement, however our case demonstrated that tumors with superficial involvement of external sphincter fibers can be resected completely.

Case presentation

A 45-year-old Caucasian male presented with a perianal mass found to be squamous cell carcinoma. Initial imaging suggested the anal sphincter was spared, however intraoperatively tumor cells were found involving superficial external sphincter fibers and a portion was excised to ensure complete removal.

Clinical discussion

Perianal squamous malignancies are often misdiagnosed as more benign conditions. Treatment aims to preserve sphincter function and depends on tumor stage along with anatomical involvement.

Conclusion

Despite superficial muscle infiltration, the T2N0 perianal lesion was curable with surgical resection alone without recurrence or functional deficits reported one year later. This suggests surgical management may be possible in some cases with sphincter involvement.

Magnetic Resonance Imaging of the Anal Region: Clinical Applications

Over the past years, magnetic resonance imaging (MRI) has become a cornerstone in evaluating anal canal and adjacent tissues due to its safeness, the three-dimensional and comprehensive approach, and the high soft-tissue resolution. Several diseases arising in the anal canal can be assessed through MRI performance, including congenital conditions, benign pathologies, and malignancies. Good knowledge of the normal anatomy and MRI technical protocols is, therefore, mandatory for appropriate anal pathology evaluation. Radiologists and clinicians should be familiar with the different clinical scenarios and the anatomy of the structures involved. This pictorial review presents an overview of the diseases affecting the anal canal and the surrounding structures evaluated with dedicated MRI protocol.

MRI of the penis

This article reviews the anatomy and magnetic resonance imaging (MRI) appearance of the penis. The recommended technique for MRI of the penis is outlined, with discussion of the benefits and drawbacks to imaging the penis after artificial erection. Common penile pathologies are reviewed, with a summary of their clinical features, MRI appearance, and treatment. The ability to demonstrate the erectile bodies and vasculature helps to evaluate vascular pathologies such as priapism, Mondor disease, and cavernosal thrombosis. MRI is also a useful tool to assess for traumatic abnormalities of the penis, with the depiction of soft tissue anatomy and fascial layers allowing for evaluation of penile fracture and penile contusion. Malignant disease of the penis is also reviewed, including squamous cell carcinoma, urethral carcinoma, metastases, and rare neoplasms. Staging of these neoplasms is addressed, with discussion of how MRI can be used to assess the extent of tumor involvement. MRI also clearly demonstrates the tunica albuginea, which allows for evaluation of Peyronie's disease.

Coexistence of Dense and Sparse Areas in the Longitudinal Smooth Muscle of the Anal Canal: Anatomical and Histological Analyses Inspired by Magnetic Resonance Images

Magnetic resonance images of the anal canal show small, circular, low‐intensity areas arranged in a row and a high‐intensity area surrounding them internally and externally in the longitudinal muscle layer that cannot be explained by current anatomical findings. The purpose of this study was to elucidate the detailed structure of the longitudinal smooth muscle of the anal canal and to interpret the magnetic resonance image of the longitudinal muscle. Specimens for macroscopic anatomy and histology were obtained from six and seven cadavers, respectively. The histological nature of the longitudinal muscle was examined by staining serial transverse and coronal sections of the lateral wall of the anal canal with Masson's trichrome stain and using immunohistochemistry for smooth and skeletal muscle fibers. Dense and sparse areas of smooth muscle fibers coexisted in the longitudinal muscle layer. The dense areas formed columnar muscle bundles approximately 1.0–1.5 mm in diameter, and they continued from the longitudinal muscle bundles of the rectum. The columnar muscle bundles of the longitudinal anal muscle were internally and externally surrounded by sparsely arranged smooth muscle fibers that ran longitudinally. The coexistence of dense and sparse areas of smooth muscle fibers suggests that the structure of the smooth muscle is optimized for its function. This histological nature is probably reflected in the magnetic resonance image of the longitudinal muscle as the coexistence of low‐ and high‐intensity areas. Clin. Anat. 33:619–626, 2020. © 2019 Wiley Periodicals, Inc.

MRI anatomy and pathology of the anal canal

The normal function of the anal sphincter complex is crucial for quality of life, as it is the mechanism by which fecal continence is maintained. Additionally, the anal sphincter complex is an integral part of the coordinated effort of defecation. As imaging plays an important role in assessment of pathologic conditions involving the anal region, understanding the normal anatomy of the anal sphincter complex is important for correct image interpretation and accurate diagnosis. This review discusses the anatomy and function of the anal sphincter complex, important technical considerations for MRI, and various inflammatory, infectious, and neoplastic processes, as well as pathologic structural conditions that affect the anal region. Level of Evidence: 5 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:1018-1032.

Can MR imaging be useful in differentiating low rectal cancer from anal cancer?

PURPOSE

To evaluate the role of pelvic MR imaging in differentiating between low rectal and anal cancers using the pathological results as the gold standard.

MATERIALS AND METHODS

In this study, retrospective analysis of 100 patients with a history of low rectal (n = 50) or anal (n = 50) cancers who underwent staging pelvic MR imaging before treatment was performed. The following parameters were analyzed: distance from the anal verge to the tumor, percentage of tumor above puborectalis muscle, tumor size, T2W signal intensity, sphincter/levator muscles invasion, organ invasion, and MRI diagnosis. Multivariable logistic regression was performed to determine factors associated with low rectal and anal cancers. Distances from the anal verge to the tumor were compared using receiver-operating characteristic (ROC) curves.

RESULTS

From the ROC curves, the cut-off value for the distance from the anal verge to the tumor in differentiating between low rectal and anal cancers was 2.1 cm and the area under the ROC curve was 0.90 (95% CI 0.84-0.97). Multivariate logistic regression revealed three significant factors in differentiating between low rectal and anal cancers, including T2 mixed hyper- and hyposignal intensity (OR 66.00, 95% CI 4.66-934.81), distance cut-off value (OR 34.72, 95% CI 5.73-210.27), and absence of sphincter invasion (OR 18.75, 95% CI 1.91-183.96), with sensitivity, specificity, PPV, and NPV of 98%, 88%, 89%, and 97%, respectively, and diagnostic accuracy increased from 79% (reader 1) and 82% (reader 2) to 93%.

CONCLUSION

MR imaging can be useful to differentiating between low rectal and anal cancers which benefits staging and treatment planning.

MRI of anal canal: common anal and perianal disorders beyond fistulas: Part 2

A broad spectrum of disease, from benign processes to life-threatening pathologies, can cause anal pain. MR imaging (MRI) has become increasingly widely used method over the past two decades for the evaluation of individuals with anorectal symptoms. Although imaging is rarely necessary to determine the etiology of the majority of cases, MRI is particularly useful as a noninvasive method of excluding severe neoplastic conditions. In this article, MRI findings of a number of pathologies such as anal and perianal neoplasms, hemorrhoidal disease, arteriovenous malformation of the perianal region, and anal sphincter lesions (defects, scarring, atrophy) which may lead to fecal incontinence are presented.