Szpak C A, Shelburne J, Linder J, Klintworth G K
Department of Pathology, Duke University Medical Center, Durham, North Carolina.
Mod Pathol. 1988 Jan;1(1):35-43.
Aside from melanomas, other nonmelanocytic pigmented tumors synthesize melanin or contain benign passenger melanocytes. While Stage IV melanosomes (mature melanosomes) occur in neoplasms which synthesize melanin as well as in those with benign companion melanocytes, Stage II melanosomes (premelanosomes), which are found in melanocytes and cells of pigmented nonmelanocytic tumors of neural crest origin, are considered the morphologic hallmark of in vivo melanin synthesis. To test this widely held concept, we studied the ultrastructure of representative malignant melanomas and other pigmented tumors (pigmented variants of the nevocellular nevus, squamous cell carcinoma, schwannoma, basal cell carcinoma, and seborrheic keratosis). Discrete intracytoplasmic Stage II melanosomes were noted in neoplastic cells of tumors of neural crest origin (melanoma, schwannoma, and nevocellular nevus), which are widely believed to synthesize melanin. In addition, they were also detected in neoplastic epithelial cells of a squamous cell carcinoma, basal cell carcinoma, and seborrheic keratosis. In these epithelial tumors, a spectrum of melanosomes from Stage II through Stage IV were presumably acquired from nonneoplastic companion melanocytes, which were an integral part of the tumor. Because squamous epithelium has not been shown to synthesize melanin, this study suggests that the finding of intracytoplasmic Stage II melanosomes does not necessarily imply melanin synthesis. When accompanied by melanocytes, epithelial and perhaps other tumors may contain ingested Stage II melanosomes.
除黑色素瘤外，其他非黑素细胞性色素肿瘤可合成黑色素或含有良性伴随黑素细胞。虽然IV期黑素小体（成熟黑素小体）存在于合成黑色素的肿瘤以及伴有良性伴随黑素细胞的肿瘤中，但II期黑素小体（前黑素小体）被认为是体内黑色素合成的形态学标志，它存在于黑素细胞以及神经嵴起源的色素性非黑素细胞肿瘤的细胞中。为了验证这一广泛认可的概念，我们研究了代表性恶性黑色素瘤和其他色素肿瘤（细胞痣的色素变体、鳞状细胞癌、神经鞘瘤、基底细胞癌和脂溢性角化病）的超微结构。在神经嵴起源的肿瘤（黑色素瘤、神经鞘瘤和细胞痣）的肿瘤细胞中发现了离散的胞质内II期黑素小体，人们普遍认为这些肿瘤能合成黑色素。此外，在鳞状细胞癌、基底细胞癌和脂溢性角化病的肿瘤上皮细胞中也检测到了II期黑素小体。在这些上皮性肿瘤中，一系列从II期到IV期的黑素小体大概是从作为肿瘤组成部分的非肿瘤性伴随黑素细胞获得的。由于尚未证明鳞状上皮能合成黑色素，这项研究表明，胞质内II期黑素小体的发现不一定意味着黑色素合成。当伴有黑素细胞时，上皮性肿瘤以及其他肿瘤可能含有摄取的II期黑素小体。
