犬口腔恶性黑色素瘤(OMMs)表现出多种形态表型,包括spindloid变体。针状体OMM的显微镜诊断是基于结合活性和/或黑色素的存在。如果没有这些功能,梭状蛋白OMM很难与软组织肉瘤(STS)区分。一种包含Melan-A的抗体混合物(MDX),PNL2和酪氨酸酶相关蛋白1和2(TRP-1和TRP-2)是当前通过免疫组织化学(IHC)鉴定无色素性OMM的金标准。然而,MDX对诊断spindloid无晶状体OMM的敏感性较低。这引起了对缺乏上覆上皮的活检标本的关注,这使得通过IHC将OMM与STS区分开可能变得困难。这项研究的目的是确定其他标记,以帮助区分缺乏色素和接合活性的STS和OMM。SOX-10最近被提出作为人类黑素细胞的敏感标记物,但尚未在狗中得到验证。同样,已经在人类中分析了各种基因的RNA表达,但不是在诊断犬黑素细胞肿瘤的背景下。对于这项回顾性研究,福尔马林固定,来自20OMM的石蜡包埋组织,20STS,选择了20个缺乏交界活性和色素沉着的口腔梭形细胞肿瘤(OSCT)。MDX的IHC,SOX-10和层粘连蛋白,与TYR的RT-qPCR平行,SOX10,CALD1,CD34,DES,和LAMA1,在所有情况下进行。TYR,CD34和CALD1是区分OMM和STS的最明显的基因,都具有100%的特异性和65%、95%和60%的灵敏度,分别。尽管对所有20个OMM进行了SOX-10的免疫组织化学标记,但也标记了两个STS(100%敏感性和90%特异性)。MDXIHC标记为所有20个OMM且无STS。令人惊讶的是,20个OSCT中没有一个表达超过截止值的TYRRNA,和14/20OSCT表达CALD1或CD34RNA高于截止值,从而确认它们为STS。四个OSCT是可疑的STS,根据IHC和RNA表达模式,没有OSCT被证实为OMM。总之,TYR的RNA水平,CD34和CALD1应在MDX阴性的可疑无色素性OMM中进行评估,以准确区分OMM和STS。
Canine oral malignant melanomas (OMMs) exhibit a variety of morphologic phenotypes, including a spindloid variant. The microscopic diagnosis of spindloid OMMs is based on junctional activity and/or the presence of melanin pigment. In the absence of these features, spindloid OMMs are difficult to differentiate from soft tissue sarcomas (STS). An antibody cocktail (MDX) that includes Melan-A, PNL2, and tyrosinase-related proteins 1 and 2 (TRP-1 and TRP-2) is the current gold standard for identifying amelanotic OMMs by immunohistochemistry (IHC). However, MDX is less sensitive for diagnosing spindloid amelanotic OMMs. This raises concern for biopsy specimens that lack overlying epithelium, making it potentially difficult to differentiate OMM from STS by IHC. The goal of this study was to identify additional markers to help differentiate between STS and OMMs that lack pigment and junctional activity. SOX-10 has recently been proposed as a sensitive marker for melanocytes in humans but has not been validated in dogs. Similarly, RNA expression for various genes has been analyzed in humans, but not in the context of diagnosing canine melanocytic neoplasms. For this retrospective study, formalin-fixed, paraffin-embedded tissues from 20 OMMs, 20 STS, and 20 oral spindle cell tumors (OSCTs) that lacked junctional activity and pigmentation were selected. IHC for MDX, SOX-10, and laminin, in parallel with RT-qPCR of TYR, SOX10, CALD1, CD34, DES, and LAMA1, was performed in all cases. TYR, CD34, and CALD1 were the most discriminatory genes in differentiating between OMM and STS, all having 100% specificity and 65, 95, and 60% sensitivity, respectively. While all 20 OMMs were immunohistochemically labeled for SOX-10, two STS were also labeled (100% sensitivity and 90% specificity). MDX IHC labeled all 20 OMMs and no STS. Surprisingly, none of the 20 OSCTs expressed TYR RNA above the cutoff, and 14/20 OSCTs expressed CALD1 or CD34 RNA above the cutoff, thereby confirming them as STS. Four OSCT were suspect STS, and no OSCTs were confirmed as OMMs based on IHC and RNA expression patterns. In conclusion, the RNA levels of TYR, CD34, and CALD1 should be evaluated in suspected amelanotic OMMs that are negative for MDX to accurately differentiate between OMM and STS.