Morphologic and Immunohistochemical Characteristics of Anorectal Melanoma

Anal carcinoma - exploring the epidemiology, risk factors, pathophysiology, diagnosis, and treatment

Anal carcinoma is a relatively rare tumor that accounts for approximately 2% of gastrointestinal malignancies and less than 7% of anorectal cancers. Most anal tumors originate between the anorectal junction and the anal verge. Risk factors for the disease include human papillomavirus infection, human immunodeficiency virus, tobacco use, immunosuppression, female sex, and older age. The pathogenesis of anal carcinoma is believed to be linked to human papillomavirus-related inflammation, leading to dysplasia and progression to cancer. Squamous cell carcinoma is the most common type of anal tumor, with an annual incidence of approximately 1 to 2 per 100000 persons. Treatment regarding anal cancer has emerged over time. However, chemoradiation therapy remains the mainstay approach for early localized disease. Patients with metastatic disease are treated with systemic therapy, and salvage surgery is reserved for disease recurrence following chemoradiation. This article aims to provide background information on the epidemiology, risk factors, pathology, diagnosis, and current trends in the management of anal cancer. Future directions are briefly discussed.

Anal intraepithelial neoplasia: a review of terminology, differential diagnoses, and patient management

Despite the knowledge of etiological association with high-risk human papilloma viruses and high-risk patient cohorts, the incidence of anal squamous cell carcinoma has continued to rise. The known precursor lesion (in particular, high-grade squamous intraepithelial lesion) makes it amenable to screening and surveillance strategies. However, the diagnosis of anal intraepithelial neoplasia suffers from interpretation challenges leading to high interobserver variability, along with numerous differential diagnoses and lingering terminology issues. Proper treatment of anal lesions requires accurate diagnosis, and while a variety of modalities are available for treatment, the rate of recurrence remains high and each modality has its own set of side effects and complications. The aim of this review article is to outline the diagnostic considerations and provide practical tips for diagnosing anal squamous intraepithelial lesions.

A Unique Case of Intracranial Amelanotic Melanoma with BRAF V600E Mutation Successfully Treated via Molecular-targeted Therapy

Melanoma carries a high risk of brain metastasis. A small subset of metastatic melanomas, known as amelanotic melanomas, does not present black coloration, reflecting a lack of melanin pigmentation. Here, we report a case of B-Raf proto-oncogene (BRAF) V600E mutation associated with a metastatic brain tumor caused by the amelanotic melanoma. A 60-year-old man was transferred to our department following acute onsets of left upper limb paralysis and convulsion. In the brain imaging, multiple lesions in the right frontal lobe and left basal ganglia were detected, and the presence of an enlarged left axillary lymph node was revealed. Consequently, we removed the right frontal lesion and performed a biopsy of the left axillary lymph node. Histological analysis of both specimens indicated an amelanotic melanoma, and genetic testing revealed a BRAF V600E mutation. The residual intracranial lesions were treated with stereotactic radiotherapy and molecular-targeted therapy, with dabrafenib and trametinib as the systemic treatment. Based on the Response Evaluation Criteria in Solid Tumors, we determined that the patient achieved complete remission (CR) under uninterrupted molecular-targeted therapy over a period of 10 months. After the temporary withdrawal of dabrafenib and trametinib to avoid hepatic dysfunction, a new intracranial lesion appeared. CR of this lesion was achieved following reinstatement of the two drugs. These results suggest that, under limited conditions, molecular-targeted therapy can produce a sustained response against the intracranial metastasis of melanoma, and the therapy with reduced dose is still effective against a recurrent case after cessation of the therapy due to the toxicity.

Clinicopathological profile and outcomes of anorectal melanoma from a tertiary care center in India

Background:

Anorectal melanoma (AM) is a rare subtype of melanoma.

Aim:

To study the clinic–pathologic features and outcomes in patients with AM.

Materials & methods:

Clinical, pathologic findings and outcomes of patients with AM were recorded.

Results:

Twenty-seven patients with AM were identified with median age of 57 years. Most patients presented in stage III (44.4%). Lymph node involvement was seen in 70.4%. The response to chemotherapy and immunotherapy was 16.6 and 25.0%, respectively. At a median follow up of 11 months, median overall survival was 30 months. Ballantine stage 3 and weight loss at presentation were predictors of poor survival.

Conclusion:

AM presents at an advanced stage with lymph node and distant metastasis.

Anorectal melanoma is a rare subset of melanoma presenting at an advanced stage with lymph node and distant metastasis. Early disease is managed surgically; however, optimal treatment of advanced disease is unclear. The stage at diagnosis is the most important prognostic factor. Prognosis is poor, but with the advent of targeted therapy and immunotherapy, the outcomes are improving.

Primary melanoma of the anorectal region: clinical and histopathological review of 17 cases. A retrospective cohort study

AIM

The aim of our study was to scrutinize diagnostic and treatment factors that may contribute to the low survival rate from anorectal melanoma while adding 17 more cases to the global research database.

METHOD

We carried out a retrospective analysis of 17 cases of anorectal melanoma treated at a single institution from 2000 to 2020. Data on patient age, sex, complaints, treatment and survival as well as tumour size, resection margins, histological and immunohistochemical features were assessed.

RESULTS

The median age of patients was 72 ± 12.49 (45-92) years. Most of the patients were women (n = 11, 64.71%). Three (17.65%) patients underwent no radical treatment. Of eight patients treated initially with radical surgery (either total mesorectal excision or abdominoperineal resection), six (75%) were found to have positive lymph nodes. Mean survival was 20 ± 23.46 (1-84) months. The average diameter of the resected tumours was 5.43 ± 3.02 cm (1.3-10 cm). Most tumours had epithelioid or spindle cell morphology and were positive for one or more melanocytic markers (S100, HMB-45 or MITF). More than half of the tumours contained no or very little melanin pigment. None of the tumours had significant lymphocytic infiltration. Three tumours showed positivity for keratins (PANCK or CAM5.2) and one tumour showed positivity for C-KIT stain.

CONCLUSION

An aggressive surgical approach may have an effect on survival in most early stages while more advanced disease benefits from a more conservative approach. Attention to sentinel lymph nodes and further systemic research into therapy is required. For now, treatment and diagnostic modalities seem to be inconsistent, requiring further investigation to elucidate common points.

Anorectal Melanoma-Brownish Black Mass Not Always a Hemorrhoid

The non-specific clinical symptoms of anorectal brownish-black mass do not help to differentiate colorectal cancer, hemorrhoids, rectal ulcers which result in a delayed diagnosis or lead to inadequate management of lethal anorectal melanoma. Primary malignant melanoma of the anorectal region is an uncommon tumor, constituting approximately 1% of anal canal tumors which may be misdiagnosed clinically as hemorrhoids. Because of aggressive behavior and poor prognosis, efficient and prompt diagnosis is required in these cases. We report 2 cases of this rare tumor.

Peripheral Palisading in Melanoma Mimicking Basal Cell Carcinoma: A Case Report

The incidence of melanoma has been increasing over the past few decades. Because of its phenotypic diversity, melanoma may present in various clinical and histopathological manifestations, and it can mimic varieties of skin lesions from benign to malignant and from epithelial to nonepithelial. Accurate diagnosis of melanoma is crucial because delayed treatment leads to worse prognoses. Here, we describe a case of melanoma in an 82-year-old man with an unusual histopathologic presentation, namely, the presence of neoplastic aggregates with a palisaded periphery resembling basal cell carcinoma.

Clinical evidence, diagnostic approach and challenging therapeutic modalities for malignant melanoma of the anorectum

Primary anorectal malignant melanoma (ARMM) is a rare, aggressive tumour that accounts for approximately 1.2% of all melanomas. This rare entity represents less than 5% of anorectal malignant tumours and 0.05-1% of all malignant colorectal neoplasms. The incidence increases with age while there is a higher prevalence in Caucasians. ARMM is often asymptomatic or presents with no disease-specific evidence so that it can mimic other rectal disorders, malignant or benign. Colonoscopy is obligatory as a diagnosing mean for ARMM. Furthermore, endoscopic ultrasonography, computed tomography and magnetic resonance imaging can be utilized for the evaluation of tumour infiltration and lymph node metastases. Moreover, diagnostic establishment of ARMM requires an undeniable demonstration of essential melanocytic features in histology and immunohistochemistry. Even though the standard of treatment remains surgical resection, the choice between wide local excision and abdomino-perineal resection is still controversial. Recently, there have been recommendations regarding new techniques which could be utilized for the surgical treatment of ARMM. Newer treatments that have been proposed such as immune-checkpoint inhibitors and targeted therapies need further validation. A multicenter study would allow clarification of the most appropriate therapeutic strategy for this uncommon nosological entity.

Primary Dedifferentiated Amelanotic Anorectal Melanoma: Report of a Rare Case

Anorectal melanoma (ARM) is an uncommon aggressive malignancy that comprises 0.5% to 1.6% of all melanoma manifestations. Dedifferentiated melanoma is very rare with loss of all melanocytic differentiation markers and is usually seen in metastatic melanoma of cutaneous origin. In this article, we report the first case of primary dedifferentiated amelanotic ARM in a 68-year-old male who presented with anal discomfort that was initially treated as inflamed hemorrhoids. Physical examination revealed a large protruding anal mass, biopsy of which showed biphasic malignant tumor cells with distinct immunoprofiles: a superficial spindled/sarcomatoid component positive for SOX10 and S100, and a deeper epithelioid/rhabdoid component positive for desmin, AE1/AE3, and EMA. Both components were negative for HMB-45, Melan-A/MART-1, c-Kit, and other lineage markers. Molecular analysis by polymerase chain reaction demonstrated wild-type BRAF and KRAS genes. A diagnosis of dedifferentiated ARM was made based on the coexistence of a differentiated component (spindled: S100 and SOX10 positive) and a dedifferentiated component (epithelioid: all melanoma markers including S100 and SOX10 negative). Shortly afterwards, the patient developed extensive pulmonary and liver metastases and expired 20 days after the diagnosis was rendered, reinforcing the highly aggressive nature of this disease entity.