T-cell-rich angiomatoid polypoid pseudolymphoma of the skin: A clinicopathologic study of 17 cases and a proposed nomenclature

Background: We describe a series of previously unreported, distinctive, polypoid solitary T-cell-rich cutaneous pseudolymphomas. Methods: The clinicopathologic features were examined in 17 cases. Results: Patient ages ranged from 16 to 71 years (mean = 38.5) with a female predominance (female: male = 14: 3). All lesions, clinically diagnosed most often as pyogenic granuloma, presented as a solitary, polypoid, erythematous, papule ranging in size from 2.5 to 7.5 mm (mean = 5.8). Most occurred on the head and neck (7) and trunk (6) with other sites including the thigh (1), shoulder (1) and knee (1). A dense dermal infiltrate composed of mildly atypical lymphocytes with variable numbers of admixed plasma cells and histiocytes was prototypical. Commonly, there was an associated epidermal collarette (16/17), Grenz zone (11/17) or admixed eosinophils (8/17). Prominent vessels lined by plump endothelial cells, reminiscent of high endothelial venules of lymph nodes, were universal and some degree of telangiectasia was also common (12/17). CD3-positive T-cells consisted of an admixture of CD4-positive and CD8-positive forms (15/16). Multiple studies suggested polyclonality (seven cases). No recurrences after lesional excision were noted in the 17 patients with a follow-up range from 24 to 120 months (mean = 46.6). Conclusion: Although these lesions share histopathologic features of the so-called acral pseudolymphomatous angiokeratoma of children (APACHE), they occur in a completely different clinical setting, present in solitary and polypoid fashion and are T-cell rich. We propose the diagnostic label T-cell-rich angiomatoid polypoid pseudolymphoma for this distinctive but presumably reactive lesion.