Terushkin Vitaly, Boyd Kevin P, Patel Rishi R, McLellan Beth
New York University School of Medicine.
Dermatol Online J. 2013 Dec 16;19(12):20711.
A 61-year-old man presented for evaluation of a bruise-like lesion of the right knee. He was found to have an ill-defined, light brown patch with focal areas of dark red and brown. The histopathologic diagnosis was consistent with amyloidosis. Further subtyping showed that the amyloid protein was AL (κ). A systemic evaluation failed to show internal involvement. Amyloidosis comprises a spectrum of diseases, which range from systemic to localized cutaneous types, and is characterized by the extracellular deposition of amyloidosis protein as beta-pleated sheets. The forms of amyloidosis are differentiated by the specific types of protein-derived amyloidosis fibers. Both nodular and primary systemic amyloidosis can present as nodules on the skin owing to deposition of AL type amyloid protein. Primary systemic amyloidosis, which carries a poorer prognosis than does nodular amyloidosis, also may give rise to ecchymoses and many other cutaneous and extracutaneous findings. Histopathologic features are similar in both cases and involve the deposition of amorphous, eosinophilic material in the dermis. Nodular amyloidosis may progress to primary systemic disease in up to 50% of cases. Because our patient had no systemic involvement and the lesions did not appear nodular in nature, the patient was given a diagnosis of primary localized AL cutaneous amyloidosis. Routine follow-up for this patient is necessary to detect any potential disease progression.
一名61岁男性因右膝出现瘀斑样病变前来评估。他被发现有一个边界不清的浅棕色斑块，伴有暗红色和棕色的局灶性区域。组织病理学诊断与淀粉样变性一致。进一步的亚型分析显示淀粉样蛋白为AL(κ)。全身评估未发现内部受累情况。淀粉样变性包括一系列疾病，从全身性到局限性皮肤型，其特征是淀粉样变性蛋白以β折叠片层形式在细胞外沉积。淀粉样变性的类型通过蛋白质衍生的淀粉样变性纤维的特定类型来区分。结节性淀粉样变性和原发性系统性淀粉样变性均可因AL型淀粉样蛋白沉积而在皮肤上表现为结节。原发性系统性淀粉样变性的预后比结节性淀粉样变性差，也可能导致瘀斑及许多其他皮肤和皮肤外表现。两种情况的组织病理学特征相似，均涉及真皮中无定形嗜酸性物质的沉积。高达50%的结节性淀粉样变性病例可能进展为原发性系统性疾病。由于我们的患者没有全身受累且病变本质上未呈现结节状，因此该患者被诊断为原发性局限性AL皮肤淀粉样变性。对该患者进行常规随访对于检测任何潜在的疾病进展是必要的。
