Poorly differentiated tumours of the anal canal: a diagnostic strategy for the surgical pathologist

Primitive rectal melanoma: A rare case report

Mucosal melanoma is a rare subtype of melanoma distinct from the cutaneous type in its clinical and biological aspects, requiring different therapeutical management. Anorectal melanomas represent less than 1% of anorectal cancers and 0.3% of malignant melanomas, and they are by far the most studied type. Proctologic examination, colonoscopy, and biopsy can establish a correct diagnosis. Imaging techniques, especially MRI can show some characteristic features, but it is essentially performed for extension assessment. We report the case of a 63-year-old man who consulted for rectal bleeding. The proctological examination found a brownish ulcerative-vegetating tumor of 3 cm in diameter located 3 cm from the anal rim. The endoscopic examination revealed a predominance of ulcerative budding lesions and the biopsy specimen confirmed a rectal melanoma. The extension assessment, based on a computed tomography scan and MRI did not show locoregional or distant metastases. Radiotherapy and abdominoperineal resection with pelvic node dissection was the treatment of choice with good evolution.

Is elective inguinal or external iliac irradiation during neoadjuvant (chemo)radiotherapy necessary for locally advanced lower rectal cancer with anal sphincter invasion?

PURPOSE

To investigate the impact of excluding irradiation of inguinal lymph nodes (ILNs) and external iliac lymph nodes (ELNs) during neoadjuvant (chemo)radiotherapy in a locally advanced lower rectal cancer (LALRC) with anal sphincter invasion.

MATERIALS AND METHODS

A total of 214 LALRC patients with anal sphincter invasion according to pre-treatment magnetic resonance imaging who underwent neoadjuvant (chemo)radiotherapy followed by surgery between September 2010 and May 2019 were enrolled. ILNs and ELNs were clinically negative pre-treatment and were excluded from irradiation. Failure rates and patterns of ILNs and ELNs and survival were analyzed. Nomograms for predicting ILN and ELN failure risk were also constructed.

RESULTS

The median follow-up was 53.3 months. The three-year failure rates were 3.7% for ILNs and 3.3% for ELNs. Only one patient developed isolated ILN failure, and no patient experienced isolated ELN failure. Multivariate analyses demonstrated that lower edge of tumors invaded or located below the dentate line (odds ratio [OR] 7.513, P = 0.013), high histological grade (OR 6.892, P = 0.017), and perineural invasion (OR 7.111, P = 0.023) were significantly related to ILN failure. Both perineural invasion (OR 8.923, P = 0.011) and high histological grade (OR 8.129, P = 0.011) showed a strong correlation with ELN failure. The concordance index of nomograms for predicting ILN and ELN failure risk were 0.842 and 0.880, respectively. The three-year local recurrence free survival, disease-free survival, and overall survival were 94.6% (95% confidence interval [CI], 91.3%‒97.9%), 77.7% (95% CI, 71.8%‒83.6%), and 91.9% (95% CI, 87.8%‒96.0%), respectively, for the whole cohort.

CONCLUSIONS

Excluding ILNs and ELNs from irradiation was associated with an acceptably low failure risk for LALRC invading the anal sphincter. These findings help to refine existing guidelines for clinical target volume delineation of ILNs and ELNs during neoadjuvant (chemo)radiotherapy in rectal cancer.

Management of Noncutaneous Melanomas

Noncutaneous melanomas are rare subtypes of melanoma with high rates of metastatic disease and poor overall survival. One-third to one-half of cases are amelanotic, which may contribute to a delay in diagnosis. Immunohistochemistry staining with typical melanoma markers helps confirm the diagnosis. There is no standard staging system across mucosal melanomas. Elective nodal dissection is not recommended and there is a paucity of data to support use of sentinel lymph node biopsy. Mutational analysis should be routinely performed. Systemic therapy options include targeted inhibitors, immunotherapy, and cytotoxic chemotherapy, although further studies are needed to confirm their efficacy.

Hellenic society of medical oncology (HESMO) guidelines for the management of anal cancer

Despite considerable improvement in the management of anal cancer, there is a great deal of variation in the outcomes among European countries, and in particular among different hospital centres in Greece and Cyprus. The aim was to elaborate a consensus on the multidisciplinary management of anal cancer, based on European guidelines (European Society of Medical Oncologists-ESMO), considering local special characteristics of our healthcare system. Following discussion and online communication among members of an executive team, a consensus was developed. Guidelines are proposed along with algorithms of diagnosis and treatment. The importance of centralisation, care by a multidisciplinary team (MDT) and adherence to guidelines are emphasised.

Anorectal mucosal melanoma

Anorectal melanoma is an uncommon and aggressive mucosal melanocytic malignancy. Due to its rarity, the pre-operative diagnosis remains difficult. The first symptoms are non-specific such as anal bleeding, anal mass or pain. Although anorectal melanoma carries a poor prognosis; optimal therapeutics strategies are unclear. Surgical resection remains the mainstay of treatment. The optimal surgical procedure for primary tumours is controversial and can vary from wide local excision or endoscopic mucosal resection (EMR) to an abdomino-perineal resection. A high degree of uncertainly exists regarding the benefit of radiation therapy or chemotherapy. The treatment of advanced melanoma is evolving rapidly with better understanding of the disease biology and immunology. Considerable effort has been devoted to the identification of molecular determinants of response to target therapies and immunotherapy.

Small Cell Carcinoma of Anal Canal - A Rare Case Report

Anal canal malignancy is one of the dreadful conditions. Most of the anal canal malignancies are squamous cell carcinomas for which the treatment is well established and the prognosis is usually favourable. Small cell carcinoma of anal canal is a very rare condition and poorly understood, which can present as haemorrhoids in its early stages and has an aggressive course. We present a case of small cell carcinoma of anal canal who underwent Abdomino Perineal Resection (APR) and chemotherapy. He developed liver metastasis during the course of chemotherapy and succumbed to the condition 4 months later.

Tumours and inflammatory lesions of the anal canal and perianal skin revisited: an update and practical approach

Tumours of the anal and perianal region are relatively rare, and clinically often interpreted as innocuous lesions, leading to frequent delays in diagnosis and adequate treatment. Although squamous cell neoplasia represents the most common entity encountered in this anatomically complex area, many conditions, both neoplastic and inflammatory, may occur. Adding to the challenge of correct diagnosis and patient management, recent years have seen major updates in the terminology of squamous cell neoplasia, created to reflect advances in our understanding of the role of human papilloma virus and unify previous terminologies used for different sites in the anogenital tract. However, squamous cell neoplasia in the anal canal and perianal region may differ in terms of histology, biological behaviour, staging and treatment. The aim of this review is to present an overview of neoplastic and non-neoplastic lesions that may be seen in this area, an update on important developments and terminology, potential pitfalls that may be encountered in routine pathology practice and a practical approach on how to resolve these issues.

An update on anal neoplasia

Although anal cancer remains a relatively uncommon tumour its frequency is rising, especially in high-risk groups. It is now well recognized that anal squamous cell carcinoma, the largely predominant tumour type, shares many similarities with cancer of the uterine cervix, with a major role for oncogenic human papilloma viruses in both tumours. Anal squamous precancerous lesions have now to be classified with the same criteria and terminology as their cervical counterparts, by using the Lower Anogenital Squamous Terminology (LAST) proposal. Only p16 protein is a useful marker in this setting at the present time. As most cases of anal cancer are treated by non-surgical procedures, pathology has a limited role in the staging of the disease, except for early lesions treated by local excision, and when the sentinel lymph node procedure is undertaken that is still under evaluation. A variety of other tumour types can occur more rarely, with difficult diagnostic issues, solved in most cases by immunohistochemistry.

Anal Melanoma With Neuroendocrine Differentiation

Melanoma of the anal cavity is an uncommon malignant tumor with an aggressive clinical behavior. The presence of nonmelanocytic cell or tissue components, designated as divergent differentiation, is an unusual but well-documented phenomenon in melanoma. We experienced a rare case of amelanotic melanoma with neuroendocrine differentiation of the anal canal, occurring in a 68-year old woman. This tumor was characterized by a clear-cut radial growth phase and an invasive component composed of a diffuse small cells population positive for neuroendocrine markers with a focal but convincing co-expression of S100 protein. To the best of our knowledge, this represents the first case of neuroendocrine differentiation in a primary melanoma of the anal cavity. Although anal melanoma with neuroendocrine differentiation is exceptional, clinical practitioners should be aware of its possibility at this site.

Metastatic squamous cell carcinoma of the anus to the lung confirmed with allelotyping

Histopathologic techniques are insufficient for distinguishing primary squamous cell carcinoma (SCC) from metastatic SCC, which is clinically important. A patient with SCC of the anus was found to also have SCC of the lung, and the question of metastatic versus synchronous primary diseases was raised. Immunohistochemical and hematoxylin and eosin (H&E) staining on sections of tissue could not discriminate between the two entities. Immunostain for p16 and chromogenic in situ hybridization for human papillomavirus (HPV) type 16 were positive in both tumors. Additionally, allelotyping for loss of heterozygosity displayed similar findings and confirmed the histopathological impression of anal SCC metastasis to the lung. The patient was treated with palliative chemotherapy instead of additional surgical treatment. When multiple tumors are present, determining metastatic versus synchronous primary tumors is necessary for appropriate treatment. Identification can be achieved using allelotyping for loss of heterozygosity.

DACT2 is a candidate tumor suppressor and prognostic marker in esophageal squamous cell carcinoma

In animals ranging from fish to mice, the function of DACT2 as a negative regulator of the TGF-β/Nodal signal pathway is conserved in evolution, indicating that it might play an important role in human cancer. In this study, we showed that tumors with higher DACT2 protein level were correlated with better differentiation and better survival rate in patients with esophageal squamous cell carcinoma. Restored expression of DACT2 significantly inhibited growth, migration, and invasion of ESCC cells in vitro, and reduced tumorigenicity in vivo. Furthermore, when DACT2 expression was restored, the activity of TGF-β/SMAD2/3 was suppressed via both proteasome and lysosomal degradation pathways, leading to F-actin rearrangement that might depend on the involvement of cofilin and ezrin-redixin-moesin (ERM) proteins. Taken together, we propose here that DACT2 serves as a prognostic marker that reduces tumor cell malignancy by suppressing TGF-β signaling and promotes actin rearrangement in ESCC.

Mixed Adenoneuroendocrine Carcinomas (MANECs) of the Gastrointestinal Tract: An Update

The systematic application of immunohistochemical techniques to the study of tumors has led to the recognition that neuroendocrine cells occur rather frequently in exocrine neoplasms of the gut. It is now well known that there is a wide spectrum of combinations of exocrine and neuroendocrine components, ranging from adenomas or carcinomas with interspersed neuroendocrine cells at one extreme to classical neuroendocrine tumors with a focal exocrine component at the other. In addition, both exocrine and neuroendocrine components can have different morphological features ranging, for the former, from adenomas to adenocarcinomas with different degrees of differentiation and, for the latter, from well differentiated to poorly differentiated neuroendocrine tumors. However, although this range of combinations of neuroendocrine and exocrine components is frequently observed in routine practice, mixed exocrine-neuroendocrine carcinomas, now renamed as mixed adenoneuroendocrine carcinomas (MANECs), are rare; these are, by definition, neoplasms in which each component represents at least 30% of the lesion. Gastrointestinal MANECs can be stratified in different prognostic categories according to the grade of malignancy of each component. The present paper is an overview of the main clinicopathological, morphological, immunohistochemical and molecular features of this specific rare tumor type.

Inguinal lymph node metastases are recognized with high frequency in rectal adenocarcinoma invading the dentate line. The histological features at the invasive front may predict inguinal lymph node metastasis

AIM

Inguinal lymph node (ILN) metastasis occurs with high frequency in some of the patients with lower rectal cancer. The aim of this study was to identify risk factors for ILN metastasis in patients with low rectal adenocarcinoma.

METHOD

We retrospectively analysed 156 patients with lower rectal adenocarcinoma who underwent radical resection (R0) at a single institution.

RESULTS

Twenty-five (16%) patients had a tumour that invaded the dentate line, seven of whom had ILN metastasis. Invasion of the dentate line was significantly associated with a high rate of ILN metastasis, worse prognosis and local recurrence than with a tumour not invading the dentate line (P = 0.03). A Cox proportional hazard regression analysis revealed the histological characteristics at the invading front (Hif) also to be a risk factor for ILN metastasis.

CONCLUSION

Tumours which invade the dentate line have a high rate of ILN metastases and worse cancer specific end-points. The presence of poorly differentiated or mucinous adenocarcinoma components is an indication for bilateral groin irradiation.

Small cell carcinoma of the anus: a case report

Small cell carcinoma of the anus is a very rare but aggressive tumour. We present a case of a 60-year old lady with small cell carcinoma of the anus. She had no metastatic disease on presentation. She had chemotherapy and radiotherapy but developed distant metastasis after completion of treatment. Immunohistochemistry is required to make a diagnosis. Chemotherapy remains the mainstay of treatment for small cell carcinoma of the anus with or without metastatic disease. Radiotherapy is for local control and relief of symptoms.

[Anal and anal margin tumors]

Tumors of the anal canal and anal margin are rare. They may raise specific problems for the pathologist. Benign tumors mainly consist of condylomas, cloacogenic polyps and fibro-epithelial polyps. Cancers are infrequent and consisted of well-differentiated squamous cell carcinoma, or poorly differentiated basaloid squamous cell carcinoma. The other malignant tumors are very rare.