Abstract：
Desmoplastic melanoma (DM), a type of spindle cell melanoma separated into pure desmoplastic melanoma (PDM) and mixed desmoplastic melanoma (MDM) subtypes, can be a diagnostic challenge and easily confused for dermal scar, especially PDM. We report a 65-year-old white man who received a left thumb amputation after an initial biopsy for melanoma, an unclassified type with epithelioid morphology. The amputation and sentinel lymph node specimens were significant for residual melanoma with epithelioid morphology, dermal scar, and a slightly expanded \"scar-like\" capsular area in one of seven lymph nodes, which was diffusely positive for SOX10 on reflex sentinel lymph node immunohistochemical protocol. On re-review of the amputation \"scar\" like area, a subsequent SOX10 stain confirmed the diagnosis of MDM in this area with epithelioid and spindle cell morphology, significantly upgrading the tumor stage. We share this case to highlight: (i) MDM, although exceptionally uncommon, can result in a pure spindle cell lymph node metastasis, (ii) to encourage increased utilization of SOX10 to assess sentinel lymph node biopsies, especially in the context of melanomas with a spindle cell component, and (iii) share an example of inattentional blindness which was fortunately identified by reflex sentinel lymph node immunohistochemical protocols.
摘要：
促纤维化黑色素瘤(DM),一种梭形细胞黑色素瘤，分为纯的促增生黑色素瘤（PDM）和混合的促增生黑色素瘤（MDM）亚型，可能是一个诊断挑战，容易混淆皮肤疤痕，尤其是PDM。我们报道了一名65岁的白人男子，他在黑色素瘤初次活检后接受了左手拇指截肢，有上皮样形态的未分类类型。截肢和前哨淋巴结标本对残留有上皮样形态的黑色素瘤有重要意义，真皮疤痕,七个淋巴结之一的“疤痕样”囊区略有扩大，在反射前哨淋巴结免疫组织化学方案中，SOX10呈弥漫性阳性。在重新审查截肢“疤痕”样区域时，随后的SOX10染色证实了MDM在该区域的诊断与上皮样和梭形细胞形态，显著提升肿瘤分期。我们分享这个案例来强调：(I)MDM，虽然异常罕见，会导致单纯的梭形细胞淋巴结转移,（ii）鼓励增加使用SOX10来评估前哨淋巴结活检，特别是在具有梭形细胞成分的黑素瘤的背景下，和（iii）分享一个疏忽性失明的例子，幸运的是通过反射前哨淋巴结免疫组织化学方案确定。
