Negbenebor Nicole A, Feller Edward
fourth-year medical student at the Alpert Medical School of Brown University.
clinical professor of medical science at Brown University.
R I Med J (2013). 2017 Sep 1;100(9):31-32.
We report an exceedingly rare case of amelanotic anorectal melanoma misdiagnosed as hemorrhoids. A 74-year-old man presented with a week's history of "blood on toilet tissue" without bowel complaints or history of cutaneous melanoma. Skin evaluation was normal. Rectal exam was negative for blood, but revealed an anal nodule, interpreted as a hemorrhoid. Hemoglobin was normal; bleeding persisted. After one month, colonoscopy detected a non-pigmented anal lesion. Biopsy showed melanoma. Noncutaneous mucosal melanoma represents 0.03% of new cancer diagnoses Anorectal melanoma accounts for 1% of melanomas and 0.4% of anal malignancies. Uncommonly, this malignancy lacks melanin pigment, complicating detection. Presenting complaints are non-specific rectal bleeding, pain, itching or incontinence, mimicking more common disorders. Dangerous misdiagnosis occurs when benign disease, not malignancy, is suspected. Risk factors for cutaneous melanoma are less frequent. Mucosal melanoma has different genetics. Clinicians must be aware of diagnostic difficulties of anorectal melanoma, especially when amelanotic. [Full article available at http://rimed.org/rimedicaljournal-2017-09.asp].
我们报告了一例极为罕见的无色素性肛管直肠黑色素瘤被误诊为痔疮的病例。一名74岁男性，有一周“卫生纸带血”的病史，无肠道不适症状，也无皮肤黑色素瘤病史。皮肤检查正常。直肠指检未发现出血，但发现一个肛门结节，被诊断为痔疮。血红蛋白正常，但出血持续存在。一个月后，结肠镜检查发现一个无色素的肛门病变。活检显示为黑色素瘤。非皮肤黏膜黑色素瘤占新诊断癌症的0.03%。肛管直肠黑色素瘤占黑色素瘤的1%，占肛门恶性肿瘤的0.4%。这种恶性肿瘤罕见地缺乏黑色素，这使得检测变得复杂。其临床表现为非特异性直肠出血、疼痛、瘙痒或失禁，类似于更常见的疾病。当怀疑为良性疾病而非恶性肿瘤时，就会发生危险的误诊。皮肤黑色素瘤的危险因素较少见。黏膜黑色素瘤有不同的遗传学特征。临床医生必须意识到肛管直肠黑色素瘤的诊断困难，尤其是无色素性的情况。[全文可在http://rimed.org/rimedicaljournal-2017-09.asp获取]
