malignant melanoma is a neoplastic disorder which results from the malignant transformation of natural melanocytes . during the neonatal period ,
these parts include the skin , meninges , mucous membranes , upper esophagus and the eyes . in all of these areas
its involvement is less than 3% of all malignant melanomas and constitutes less than 1% of all tumors of the anorectal area .
however , the most common site for development of melanoma in the alimentary tract is the anorectal area . the first case of this disease
the most important factor in predicting survival is the disease stage at the time of diagnosis .
invasive methods such as abdominoperineal resection ( apr ) and bilateral inguinal lymphadenectomy are less suggested today due to the low survival rate of this condition . nowadays , in cases in which adequate margin is available , less invasive techniques besides preserving the sphincter are more commonly recommended . in the various studies
performed so far , the overall survival rate of the patients treated with these two methods did not show any significant difference .
nevertheless , it seems that the local control in patients treated with the apr surgical method is better and the recurrence rate is lower .
the records of anorectal melanoma cases referred to omid oncology center , mashhad , iran , from 2001 to 2011 were extracted and studied .
all required data were gathered from the files and their present general condition was recorded by calling each and every patient by phone .
one patient had been referred with complaints of pain in the perineal area and the rest with the chief complaint of rectorrhagia . in two patients ,
melanoma had been diagnosed with hemorrhoids and the melanomas were confirmed after surgery and pathology assessment . in our study ,
two cases had been referred with initial diagnosis of lymphoma which in complementary studies with immunohistochemistry ( ihc ) and examining the tissue sample following surgery , the diagnosis of melanoma had confirmed ( figure 1 , 2 ) .
three of the seven patients ( 43% ) had distant metastases to the liver , lungs , omentum and mesentery whereas another 4 ( 57% ) had locally advanced disease . in patients with locally advanced stages , 2 cases serosa ( figure 3 ) , in one case , pelvic lymph nodes and in one case
four cases had undergone apr surgery alone with curative intent . in these cases , we recommended adjuvant radiotherapy for two patients after apr due to lymphadenopathy based on pathology reports .
palliative chemotherapy had been administered in two patients to lessen metastases symptoms . at the time of data analysis
only 2 cases were alive . after 8 and for another 15 months of follow up
for all patients , the median survival was 4 month ( range 1 - 15mo ) ( table 1 ) .
the anorectal area is the third most common site for melanoma after the skin and eye . in the recent years
, the incidence of this condition has raised in the young male population . in a study conducted on 117 cases in the u.s . , the probable association between anorectal melanoma and hiv has been proposed [ 4 , 5 ] .
nevertheless , most of cases of this disease occur in the 5th or 6th decades of life . in the present study ,
the mean age of the studied cases was 64 years which is consistent with the global age ranges for this condition .
the common and usual manifestations of this condition are rectal haemorrhage and changes in the defecation habits .
such symptoms are also the most common manifestations of other benign diseases of this area including hemorrhoids , fissures and polyps . in our investigation ,
one patient had been referred with complaints of pain in the perineal area and the rest with the chief complaint of rectorrhagia .
such lesions are often fully diagnosed following a simple surgical procedure . in the present investigation
on macroscopic evaluation , the anorectal melanoma manifests with a pigmented or non - pigmented polypoid mass .
when microscopically viewed , it is seen as cellular nests which are diagnosed by specific staining against melanosomal proteins ( immunostaining ) .
the level of invasiveness and malignancy of anorectal melanoma is defined by the short disease - free survival time ( dfs ) , the overall survival and the high rate of metastasis . around 26% of the cases had distant metastases at the time of diagnosis .
three of the seven patients ( 43% ) had distant metastases to the liver , lungs , omentum and mesentery while the other ( 57% ) had advanced local disease .
in the current study , the mean time between the onsets of symptoms to confirmation of the final diagnosis was 8 months and the median survival following diagnosis was 4 months .
this high rate of metastasis could be due to the delay in diagnosing the disease . in cooper
et al study on 65 cases with anorectal melanoma , the mean duration of symptoms before diagnosis was 5.3 months and 38% of the cases had distant metastatic disease at the time of diagnosis .
the number of anorectal melanoma patients even in major oncology centers is limited . in general , one case is reported every year from each center .
apr could be the definite cure for lesions with a less than 2 mm invasion depth .
this is based on the hypothesis that this disease spreads through the submucosal lymphatic system and the mesenteric lymph nodes .
therefore , the apr surgical method could be proposed as the method of choice in such patients .
radiotherapy is considered as a palliative treatment in tumors with extensive involvement and often unresectable or in cases in whom surgery is contraindicated due to other underlying medical disorders . in metastatic patients , the combination of radiotherapy and chemotherapy can be applied as a palliative treatment .
overall , the prognosis of anorectal melanoma seems to be poor and the delay in diagnosis leads to high disease stage at the time of treatment .
most probably distant micro - metastases had been occurred in our cases ( 4 patients ) who presented locally advanced .
anorectal melanoma is a rare disease and should be considered as an uncommon differential diagnosis for lesions in this area to prevent misdiagnosis .
better results could be further achieved by the close cooperation of different related specialties which could lead to the earlier diagnosis and better prognosis in such cases .
anorectal melanoma is a rare disease and should be considered as an uncommon differential diagnosis for lesions in this area to prevent misdiagnosis .
better results could be further achieved by the close cooperation of different related specialties which could lead to the earlier diagnosis and better prognosis in such cases .
 backgroundanorectal melanoma is one of the rare but significant malignancies of the anorectal area . 
 this malignancy currently accounts for 1% of all types of melanoma and less than 1% of all the anorectal area malignancies . 
 very rare cases of this disease have been reported worldwide.anorectal melanoma is mostly diagnosed while treating other benign conditions of this area such as hemorrhoids with conventional modalities . 
 its treatment of choice has always been a controversial issue.methodsin this study , clinical pathology and outcome of 7 cases with anorectal melanoma referred to omid oncology teaching hospital during 2001 - 2011 were assessed.resultsout of seven cases , 2 patients had been diagnosed with hemorrhoids and undergone surgery and 2 other cases had been referred with the primary diagnosis of lymphoma . 
 initially , only in 3 cases melanoma was diagnosed in clinicopathology setting . 
 three cases of patients had distant metastases to the liver , lungs , omentum and mesentery , while the other 4 patients had advanced local disease . 
 no patient had been diagnosed in the primary stages of the disease . 
 the mean time duration between symptoms onset to diagnosis of disease had been 8 months . 
 the median survival time was 5 months.conclusionrare anorectal melanoma and its similar manifestations to other common anorectal conditions can delay the diagnosis , therefore should be considered as an uncommon differential diagnosis . 
 the disease 's outcome is poor and most probably delay in the diagnosis has an important role in the treatment results . 
Introduction
Materials and Methods
Results
Discussion
Conclusion