Anorectal melanoma

from Wikipedia, the free encyclopedia
Classification according to ICD-10
C43.5 Malignant melanoma of the trunk; Anus: skin, edge (area); Skin of the mammary gland; Perianal skin
ICD-10 online (WHO version 2019)
Rectum and anal canal with anorectal melanoma that was removed by abdominoperineal rectal extirpation (complete removal of the sigmoid colon, rectum and sphincter apparatus) in a 55-year-old patient.
Photo of another anorectal melanoma in a 57-year-old patient that was also removed by abdominoperineal rectal extirpation.
Histological preparation of the anorectal melanoma of the 57-year-old patient. The melanin pigmentation and the spindle-shaped melanocytes are clearly visible .

The anorectal melanoma , also called anorectal malignant melanoma called, is a rare cancer in the range of After and rectum . In contrast to the much more common cutaneous malignant melanoma (black skin cancer), it belongs to the group of mucosal ('belonging to the mucous membrane') melanoma.

description

Anorectal melanoma is a highly malignant tumor that develops from degenerate melanocytes (pigment cells) of the anoderm (anal skin). Most tumors develop in the anal canal in the area of ​​the dentate line , or somewhat below this borderline between the anoderm and epithelium of the rectum. There they spread below the mucous membrane into the distal rectum. Compared to the much more common cutaneous malignant melanomas, anorectal melanomas grow much more aggressively and faster.

Epidemiology

About 1 to 3% of all malignant melanomas occur in the area of ​​the anorectum (anus and rectum). The anorectal melanoma accounts for 0.25 to 1.25% of all malignant tumors in this area. It is therefore an extremely rare cancer. Up to 1982 only 170 and up to 2000 fewer than 300 cases had been published. Other authors reported over 800 cases in the literature to date in 2004. Men and women are affected roughly equally, Africans significantly less often than Europeans. However, due to the rarity of the disease, the data are relatively poor. The largest epidemiological study on anorectal melanoma comes from the United States. According to this, the average age of the sick is in the range of 66 years (± 16 years). The average age has decreased since 1985. Since then, the incidence has also increased significantly from 0.19 per 1 million population and year (in the years 1973 to 1983) to 0.385 per 1 million population and year. In the greater San Francisco area , the incidence in the group of 25 to 44 year old men was particularly high from 1988 to 1992 at 1.44 per 1 million population. The comparatively high local incidence in men is attributed to the involvement of infections with the human immunodeficiency virus (HIV), which was also relatively high in this area compared to the rest of the USA during the survey period.

After the skin organ, which is by far the most common site of malignant melanoma, and the eye , the anal canal is the third most common location for malignant melanoma. Primary anorectal melanoma is more common than metastases of cutaneous melanoma in the anus and rectum.

Etiology and pathogenesis

The etiology of anorectal melanoma is largely unclear. While in cutaneous malignant melanoma, by far the most common malignant melanoma, there is a clear correlation between the dose of sun or ultraviolet radiation that the skin has received since birth and the risk of cancer, this is not the case with anorectal melanoma. The anorectal area is also largely protected from harmful radiation. In the Australian state of Queensland , which has the highest incidence of cutaneous malignant melanoma in the world, the anorectal variant is just as rare as in the rest of the world. Solar radiation is therefore neither a risk factor nor does it have a preventive character for anorectal melanoma . Other risk factors for cutaneous malignant melanoma, such as xeroderma pigmentosum or dysplastic nevus syndrome , also have no influence on the likelihood of developing anorectal melanoma.

All melanomas originate from melanocytes, which are formed in the neural crest in the embryonic state and migrate to many parts of the body during fetal development . They are found primarily in the skin, but also in the eyes ( retina and choroid ) and mucous membranes (head and neck region, anorectum and female genitals ). As a result of largely unknown external stimuli, these cells can degenerate, some of them escape the immune system and, in further carcinogenesis, develop into a malignant tumor.

When cutaneous melanoma is often very a Ras - mutation , especially in codon 61 of NRAS , above. This mutation is rarely seen in anorectal melanoma.

Symptoms

The main symptom of anorectal melanoma is more or less severe rectal bleeding . Those affected also complain of swelling, anal oozing and pain. These symptoms are very similar to those of the widespread hemorrhoid disease . This often leads to the symptoms of anorectal melanoma being diagnosed (self) and treated (self) as 'hemorrhoids'. It takes an average of five months from the first symptoms to the correct diagnosis, so that in many patients a metastasis has already taken place, which significantly worsens the prognosis . It is estimated that 40 to 70% of patients have already metastasized to the lymph nodes or other organs at the time of initial diagnosis.

In later stages of the disease, those affected may feel a foreign body in the rectum. In addition, there are pain and irregularities in bowel movements and anal itching ( pruritus ani ).

diagnosis

Anorectal melanoma can develop in any position of the anorectum. The rectum is preferred to about 35%. This is followed by the anal canal with about 21% and the anal edge with 15%. In the remaining 29%, the site of origin can no longer be determined because the tumor has already manifested itself in at least two zones.

Most anorectal melanomas are broad-based on the mucous membrane. Less often they present themselves as pedunculated, polyp-like (polypous) tumors. They can vary in size from a few millimeters to over 100 mm. The tumors can ulcerate and several can be present in the anorectum. They usually have a blackish hue, but 20 to 50% of anorectal melanomas are not pigmented, that is, amelanotic . In this case, the risk of confusion with other new tissue formations or hypertrophies is particularly high.

After digital rectal palpation and proctoscopy , imaging techniques are usually used to further assess the disease. With the endorectal sonography (ultrasound examination) the infiltration depth of the tumor can be determined. A possible metastasis can be clarified using computed tomography (CT) and magnetic resonance imaging (MRT).

In laboratory medicine , the immunohistological tumor markers S-100 protein , HMB-45 , Melan A and microphthalmia-associated transcription factor (MITF) can be used to make a diagnosis. Histologically, the degenerate melanocytes are extremely polymorphic (varied). For example, pleomorphic and in some cases multinucleated tumor giant cells as well as globoid or spindle-like cell clusters can be observed. Amelanotic tumors or tumor cells without junctional changes cannot be adequately diagnosed with conventional histology.

Because of the rarity of anorectal melanoma, there is no established TNM classification for this cancer. A simplified classification adopted by many working groups provides for three stages:

  • Stage I: local growth
  • Stage II: lymph node metastasis
  • Stage III: distant metastasis

It is not uncommon for anorectal melanoma to be the incidental finding of a hemorrhoidectomy .

On average, it takes four to six months from the first symptoms to the doctor's visit. This is due, among other things, to the patients' feelings of shame . The anorectal area is taboo for many . On the other hand, the symptoms are classified as less severe and are usually assigned to much more harmless diseases, such as hemorrhoids, skin tags or condylomas .

Due to the late diagnosis and the aggressive tumor growth, the cancer is already well advanced in many patients at the time of the initial diagnosis and the prognosis is therefore extremely poor. At this point the tumors are over 1 cm thick and mostly ulcerate. The tumors metastasize preferentially to the lymph nodes of the groin and mesentery . At the time of diagnosis, around a third of patients already have metastases. In addition to the lymph node areas mentioned, the liver , lungs , skin and brain in particular are affected by metastases.

therapy

Surgical removal of the tumor is the treatment of choice. Two fundamentally different methods can be used:

To date, it is unclear which method delivers the better results with regard to the mean survival rate for the patient. Because of the rarity of the disease, there are no randomized comparative studies and too few patients without metastases at the time of the operation. In most cases, the surgical procedure is purely palliative . A cure is no longer possible. In terms of quality of life - keyword: permanent enterostomy - abdominoperineal extirpation of the rectum is clearly inferior to the much less morbid, wide local excision. Regardless of the surgical procedure, there are no long-term survivors with metastases in the lymph nodes or other organs. Some authors therefore recommend abdominoperineal rectal extirpation only in the event of a relapse or if excision is not possible in a healthy area.

A lymphadenectomy (removal of lymph nodes) is usually performed when there is evidence of an involvement of the lymph nodes. A purely prophylactic removal of the lymph nodes is not beneficial and is rejected by many authors.

The therapeutic success of adjuvant therapies , such as pre- or postoperative radiation or chemotherapy , as well as cancer immunotherapy , for example with interferon α-2b , interleukin-2 (IL-2) or Bacillus Calmette-Guérin (BCG) is not certain and not standardized.

forecast

The prognosis for anorectal melanoma is extremely poor. The five year survival rate is in the range of 5 to 20%. The median survival was between 12 and 25 months. Age, gender, and ethnicity do not affect survival. Even early incidental findings of non-symptomatic anorectal melanomas, for example after a hemorrhoid or polypectomy (removal of intestinal polyps), or tumors with a diameter of less than 2 cm have an extremely poor prognosis. The type of surgical treatment also has no influence on the survival rate.

Initial description

Anorectal melanoma was first described in 1857 by WD Moore at London's Middlesex Hospital in a 65-year-old patient.

further reading

Individual evidence

  1. ↑ S. Liptrot, D. Semeraro include: Malignant melanoma of the rectum: a case report. In: Journal of medical case reports. Volume 3, 2009, pp. 9318, ISSN  1752-1947 . doi : 10.1186 / 1752-1947-3-9318 . PMID 20062747 . PMC 2803841 (free full text).
  2. ↑ a b C.N. Stoidis, BG Spyropoulos include: Diffuse anorectal melanoma; review of the current diagnostic and treatment aspects based on a case report. In: World journal of surgical oncology. Volume 7, 2009, p. 64, ISSN  1477-7819 . doi : 10.1186 / 1477-7819-7-64 . PMID 19671138 . PMC 2731760 (free full text).
  3. ↑ a b c d e f g h i B. M. Helmke, HF Otto: The anorectal melanoma. In: The Pathologist. Volume 25, Number 3, May 2004, pp. 171-177, ISSN  0172-8113 . doi : 10.1007 / s00292-003-0640-y . PMID 15138698 . (Review).
  4. ↑ CM Fenoglio-Preiser, AE Noffsinger and others: Gastrointestinal pathology. An atlas and text. 2nd edition, Lippincott-Raven, 1998, ISBN 0-397-51640-1 , pp. 1120-1125.
  5. ↑ a b c d e f g h i j K.-H. Ebert, HJ Meyer: Anorectal Malignant Melanoma. In: Coloproctology . Volume 23, number 4, 2001, pp. 220-224, doi : 10.1007 / PL00001898
  6. ↑ a b J.-O. Gebbers, W. Remmele: Anal region. Chapter 8 in: W. Remmele (Ed.): Pathology 2: digestive tract. 2nd edition, Gabler Wissenschaftsverlage, 1996, ISBN 3-540-60119-8 , p. 701. Restricted preview in the Google book search
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  23. ↑ a b P. H. Cooper, SE Mills, MS Allen: Malignant melanoma of the anus: report of 12 patients and analysis of 255 additional cases. In: Diseases of the Colon and Rectum . Volume 25, Number 7, October 1982, pp. 693-703, ISSN  0012-3706 . PMID 7128372 .
  24. ↑ GH Weyandt, AO Eggert et al.: Anorectal melanoma: surgical management guidelines according to tumor thickness. In: British journal of cancer . Volume 89, Number 11, December 2003, pp. 2019-2022, ISSN  0007-0920 . doi : 10.1038 / sj.bjc.6601409 . PMID 14647131 . PMC 2376860 (free full text).
  25. ↑ CL Slingluff, RT Vollmer, HF Seigler: Anorectal melanoma: clinical characteristics and results of surgical management in twenty-four patients. In: Surgery. Volume 107, Number 1, January 1990, pp. 1-9, ISSN  0039-6060 . PMID 2296748 .
  26. ↑ B. Ceccopieri, AR Marcomin et al: Primary anorectal malignant melanoma: report of two cases. In: Tumori. Volume 86, Number 4, 2000 Jul-Aug, pp. 356-358, ISSN  0300-8916 . PMID 11016729 . (Review).
  27. ↑ JT Droesch, DR Flum, GN Mann: Wide local excision or abdominoperineal resection as the initial treatment for anorectal melanoma? In: American journal of surgery. Volume 189, Number 4, April 2005, pp. 446-449, ISSN  0002-9610 . doi : 10.1016 / j.amjsurg.2005.01.022 . PMID 15820458 . (Review).
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  29. ↑ A. Trupka, M. Siebeck, M. Volkenandt: Anorectal malignant melanoma. In: M. Volkenandt, G. Plewig (Hrsg.): Manual Malignant Melanome - Recommendations for diagnosis, therapy and follow-up care. 5th edition, Zuckschwerdt, 2000, ISBN 3-886-03697-9 , pp. 116-118.
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  33. ^ W. Moore: Recurrent melanoma of the rectum after previous removal from the verge of the anus in a man aged sixty-five. In: The Lancet. Number 1, 1857, p. 290.