Jordaan H F, Schneider J W
Department of Dermatology, Faculty of Medicine, University of Stellenbosch, Tygerberg Hospital, South Africa.
Am J Dermatopathol. 1997 Apr;19(2):119-26. doi: 10.1097/00000372-199704000-00004.
Papular urticaria is the result of hypersensitivity (id-reaction) to bites from certain insects such as mosquitoes gnats, fleas, mites, and bedbugs. Papular urticaria is common in childhood and is characterized by symmetrically distributed pruritic papules and papulovesicles. Scratching causes erosions and ulcerations. Pyoderma is common. Lesions occur in crops. The histopathologic features of papular urticaria are inadequately documented. In a prospective study we recorded the histopathologic features of 30 patients (female, 18; male, 12) with papular urticaria. Their ages ranged from 6-343 months (median = 21 months, mean = 37.73 months). Features that presented in more than 50% of cases included mild acanthosis, mild spongiosis, exocytosis of lymphocytes, mild subepidermal edema, extravasation of erythrocytes, a superficial and deep mixed inflammatory cell infiltrate of moderate density, and interstitial eosinophils. We recognized lymphocytic (n = 4), eosinophilic (n = 9), neutrophilic (n = 7), and mixed (n = 9) subtypes. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded sections from 10 cases and revealed abundant T-lymphocytes (CD45RO, CD3) and macrophages (CD68) in all cases. B-lymphocytes (CD20) and dendritic antigen-presenting cells (S100) were absent. Direct immunofluorescence staining was conducted on cryostat-prepared sections from 26 specimens. Deposition of IgA, IgG, IgM, C3, and fibrin could not be demonstrated. The histopathologic differential diagnosis of papular urticaria includes other spongiotic dermatitides, pityriasis lichenoides et varioliformis acuta, the pruritic papular eruption of human immunodeficiency virus disease, and papulonecrotic tuberculid. Papular urticaria with marked spongiosis and a dense inflammatory cell infiltrate cannot be reliably distinguished from arthropod bites on clinical and histopathologic grounds. The present study provides morphologic and immunohistochemical evidence that a type I hypersensitivity reaction plays a central role in the pathogenesis of papular urticaria. The putative antigen remains undetermined.
丘疹性荨麻疹是对某些昆虫叮咬（如蚊子、蠓、跳蚤、螨虫和臭虫）产生的超敏反应（自身反应）的结果。丘疹性荨麻疹在儿童期很常见，其特征是丘疹和丘疱疹对称分布且伴有瘙痒。搔抓会导致糜烂和溃疡。脓疱病很常见。皮损成批出现。丘疹性荨麻疹的组织病理学特征记录不足。在一项前瞻性研究中，我们记录了30例丘疹性荨麻疹患者（女性18例，男性12例）的组织病理学特征。他们的年龄在6至343个月之间（中位数 = 21个月，平均 = 37.73个月）。超过50%的病例出现的特征包括轻度棘层肥厚、轻度海绵形成、淋巴细胞外渗、轻度表皮下水肿、红细胞外渗、中度密度的浅表和深部混合性炎性细胞浸润以及间质嗜酸性粒细胞。我们识别出淋巴细胞型（n = 4）、嗜酸性粒细胞型（n = 9）、中性粒细胞型（n = 7）和混合型（n = 9）亚型。对10例经福尔马林固定、石蜡包埋切片进行免疫组织化学检测，结果显示所有病例均有丰富的T淋巴细胞（CD45RO、CD3）和巨噬细胞（CD68）。无B淋巴细胞（CD20）和树突状抗原呈递细胞（S100）。对26份冷冻切片进行直接免疫荧光染色。未发现IgA、IgG、IgM、C3和纤维蛋白的沉积。丘疹性荨麻疹的组织病理学鉴别诊断包括其他海绵状皮炎、急性痘疮样苔藓样糠疹、人类免疫缺陷病毒病的瘙痒性丘疹疹以及丘疹坏死性结核疹。临床上和组织病理学上，具有明显海绵形成和密集炎性细胞浸润的丘疹性荨麻疹无法与节肢动物叮咬可靠区分。本研究提供了形态学和免疫组织化学证据，表明I型超敏反应在丘疹性荨麻疹的发病机制中起核心作用。假定的抗原仍未确定。
