武汉市第三医院皮肤科彭才智

梅毒的基本病变主要是①血管内膜炎，内皮细胞肿胀与增生；②血管周围炎，有大量淋巴细胞与浆细胞浸润。晚期梅毒除上述变化外，尚有上皮样细胞和巨细胞肉芽性浸润，有时有坏死。
　　一、硬下疳：呈血管周围浸润性病变，主要见淋巴细胞，包括CD8+和CD4+细胞、浆细胞和组织细胞，伴有毛细血管内皮的增生，随后出现小血管闭塞。此外，梅毒螺旋体见于疳中的上皮细胞间隙中、毛细血管以及淋巴管周围和局部淋巴结中。
　　二、二期梅毒斑丘疹；特征是表皮角化过度，有中性多形核白细胞侵入真皮乳头，真皮深层血管周围有单核细胞、浆细胞和淋巴细胞浸润。
　　三、扁平湿疣：早期为表皮疣状增生，晚期中央组织坏死，乳头延长，真皮有炎性浸润。血管周围有明显的浆细胞浸润，呈袖口状排列，毛细血管增生，伴表皮细胞内外水肿。用银染色法在扁平湿疣中约有1/3病例找到梅毒螺旋体，主要位于表皮内，少数位于浅血管周围。
　　四、三期梅毒：主要为肉芽肿性损害，血管变化较二期轻微，为上皮样细胞及巨噬细胞组成的肉芽肿，中间可有干酪样坏死，周围大量的淋巴细胞与浆细胞浸润，并有一些成纤维细胞和组织细胞，血管内皮细胞常有增生肿胀，甚至管腔堵塞。
　　五、结节性梅毒疹与树胶肿的区别在于病变的广泛程度与位置的深浅。结节性梅毒疹肉芽肿局限于真皮内，干酪样坏死轻微或缺如，大血管不受累；树胶肿的病变广泛，可累及皮下，干酪样坏死明显，大血管亦常受累。

Histologic Findings

• Primary syphilis: Skin and mucosal lesions show a perivascular and perijunctional infiltrate of lymphocytes, plasma cells, and macrophages. At times, capillary endothelial proliferation and subsequent obliteration of small blood vessels may be appreciable. Focal erosion or ulceration is common.
• Secondary syphilis: Skin lesions are typified by a "lichenoid-psoriasiform" configuration with a perijunctional infiltrate of lymphocytes, histiocytes, and plasmacytes. Often the histiocytic component of the infiltrate is prominent and thus the biopsy may assume a "lichenoid-granulomatous" configuration. Small numbers of neutrophils may be included in the perijunctional infiltrate, and neutrophils may also be present in an expanded overlying stratum corneum. Organisms are readily demonstrable using T pallidum immunoperoxidase staining during the secondary stage.
• Tertiary lesions: Gummas consist of granulomatous inflammation with central necrosis flanked by plump or palisaded macrophages and fibrocytes surrounded by large numbers of mononuclear leukocytes, including many plasma cells. Treponemes may be scant in gummas and are sometimes difficult to demonstrate. Aortitis reveals inflammatory scarring of the tunica media, secondary to obliterative endarteritis of the vasa vasorum. Uneven loss of the medial elastic fibers and muscle cells may be evident.