Pigmented anal squamous intraepithelial neoplasia: a case report and review of literature

摘要: Squamous cell carcinoma (SCC) of the anal canal is a rare malignant neoplasm, and non-invasive squamous intraepithelial neoplastic lesion referred to as neoplasia (ASIN), which considered precursor invasive SCC [1]. Most cases ASIN are associated with human papilloma virus (HPV) infection, acquired immunodeficiency syndrome (HIV)-positive individuals at high risk development [1]. Albeit rare, it has been well recognized that various non-melanocytic neoplasms accompany non-neoplastic melanocytes within tumor, this phenomenon described “melanocytic colonization” [2-12]. or in situ (squamous neoplasia) occasionally accompanies lesion, pigmented [8,10]. Herein, we describe first documented case high-grade ASIN. A 43-year-old Japanese male HIV presented persistent bloody stool. He had past history nontuberculous mycobacterial infection lymph nodes. Colorectal endoscopic examination demonstrated villous from anus (Figure 1). Biopsy was performed under clinical diagnosis condyloma acuminatum. Figure 1 Endoscopic feature showing canal. Histopathological study biopsy specimen revealed proliferation atypical cells entire layer epithelium 2A). These mildly- moderately-enlarged round nuclei small nucleoli 2B). Mitotic figures were observed upper portion epithelium. No growth noted. A peculiar finding present presence dendritic without atypia, no mitotic 2B). Figure 2 Histopathological features canal. A. Proliferation HE, x 200. B. have ... Immunohistochemical studies using an autostainer (Ventana) by same method previously reported [13-17]. The positive for S-100 protein Melan-A 3A), some them also HMB-45. diffusely p16 3B), Ki-67-positive epithelium. Figure 3 Immunohistochemical findings expressed melanocytes, epithelium, 200. Accordingly, ultimate made. Pigmented (SCC situ) organs [2,8,18,19]. Pigmented skin (pigmented Bowen’s disease) rarely [18,19]. Ragi et al. 7 420 lesions disease (1.67%) [18]. Moreover, few normally do not any such esophagus uterine cer vix [2,8]. Normal melanocytes. Clemmensen Fenger assessed immunohistochemical methods [20]. Melanocytes frequently normal zone, only sporadically transitional but colorectal zone ASIN. Non-neoplastic may derived surrounding canal. The concise mechanism melanocytic colonization completely resolved. However, Satomura oral mucosa can produce melanocyte chemotactic factors, stem factor endothelin-1, resulting tumor [21]. Additional needed clarify pathogenesis melanocytes. p16 cyclin-dependent kinase inhibitor prevents phosphorylation retinoblastoma suppressor protein, conditions, inhibits cycle. expression up-regulated high-risk HPV strong diffuse immunoreactivity found almost all cervix [22]. Recent immunostaining very useful marker [23,24]. Almost show p16, suggests Although analysis case, involvement HPV.