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

T-Cell-Rich Angiomatoid Polypoid Pseudolymphoma: A Case Report and Comparison With Key Differential Diagnoses

T-cell-rich angiomatoid polypoid pseudolymphoma (TRAPP) is a rare and recently defined entity, conceptualized just over a decade ago. Recognition of TRAPP is important because it can be clinically and microscopically confused with low-grade cutaneous lymphomas and other vascular proliferations. We report a case of a 28-year-old male with a solitary 1.2 cm red polypoid papule on the middle posterior base of the neck. The histopathological examination revealed a well-circumscribed dermal nodular proliferation of banal-appearing lymphovascular spaces with plump endothelial cells. Immunohistochemical analysis showed a T-cell-rich infiltrate. The clinical-pathological differential diagnosis for TRAPP includes pyogenic granuloma, angiolymphoid hyperplasia (epithelioid hemangioma), acral pseudolymphomatous angiokeratoma of children, cutaneous lymphoid hyperplasia, and low-grade cutaneous lymphomas and lymphoproliferative disorders. We review the literature and discuss the key differentiating features between TRAPP and its common differential diagnoses.

Inflammatory Lobular Hemangioma (T-cell Rich Angiomatoid Polypoid Pseudolymphoma) - Assessment of FOS/FOSB and Lymphoid Markers and Comparison with Epithelioid Hemangioma

BACKGROUND

T-cell rich angiomatoid polypoid pseudolymphoma (TRAPP) and inflammatory lobular hemangioma (ILH) encompass a spectrum of cutaneous vascular lesions in which a prominent lymphoplasmacytic component may impart a pattern highly reminiscent of low-grade cutaneous lymphoma (pseudolymphoma). Epithelioid hemangioma, including its most common variant angiolymphoid hyperplasia with eosinophilia (ALHE), is a distinct entity associated with FOS and/or FOSB expression detected by immunohistochemistry (IHC). These entities can show significant morphological overlap.

METHODS

We performed IHC for FOSB, FOS and lymphoid markers in a series of TRAPP/ILH and ALHE.

RESULTS

We identified 13 cases of ILH/TRAPP, which showed a predominance in CD8+ T cells (CD8>CD4: 11/13) while FOSB and FOS were expressed in 36% (4/11) and 27% (3/11) of cases, respectively. ALHE (n=9) showed a predominance in CD4+T cell (67%) with FOSB and FOS co-expression in 78% (7/9) of the cases.

CONCLUSION

We demonstrated, based on FOS and/or FOSB immunohistochemical expression, that there is a possible link between ILH/TRAPP and epithelioid hemangioma / ALHE. The use of FOS and FOSB IHC in the routine diagnostic setting of cutaneous vascular lesions will help to redefine cases of ILH/TRAPP as a subset of these may represent inflammatory variants of epithelioid hemangioma.

Inflammatory lobular hemangioma: A vascular proliferation with a prominent lymphoid component. Review of a series of 19 cases

In the last 30 years, there has been a strong interest in vascular proliferations. Pyogenic granuloma was not only renamed lobular capillary hemangioma, but also the conceptual interpretation was also changed from an overgrowth of granulation tissue to a genuine hemangioma (or benign vascular neoplasm). We describe 19 cases of patients who presented clinically with a vascular lesion, characteristically a pyogenic granuloma or lobular hemangioma, where the histopathological findings led to the pathologic concern for a lymphoma of the skin. These benign lesions with a dense lymphoid infiltrate were further defined on the basis of different vascular and lymphoid immunohistochemical markers as inflammatory lobular hemangiomas. We propose that given the considerable histopathological overlap between acral pseudolymphomatous angiokeratoma, T-cell rich angiomatoid polypoid pseudolymphoma of the skin, and other designations of some of these vascular proliferations with a rich and dense lymphoid infiltrate, they might constitute a spectrum of vascular lesions with varying clinical presentations.

Use of topical rapamycin in acral pseudolymphomatous angiokeratoma of children (APACHE): A report of two cases and review of the literature

Acral pseudolymphomatous angiokeratoma of children (APACHE) is a rare, benign disease characterized clinically by multiple, asymptomatic, erythematous papules in the acral regions. We report APACHE in a 12-year-old girl with erythematous-violaceous papules on the lateral dorsum of her foot and toes, and a 3-year-old girl with erythematous papules on the plantar aspect of her foot. Topical rapamycin ointment improved the lesions and both patients tolerated the medication well. Topical rapamycin appears to be a potentially efficacious, well-tolerated, non-invasive therapy in APACHE, although further studies are needed.

Expression of Peripheral Node Addressins by Plasmacytic Plaque of Children, APACHE, TRAPP, and Primary Cutaneous Angioplasmacellular Hyperplasia

High-endothelial venules are a common feature of 3 types of cutaneous pseudolymphomas: pretibial lymphoplasmacytic plaque (PLP) of children, acral pseudolymphomatous angiokeratoma of children (APACHE), and T-cell rich angiomatoid polypoid pseudolymphoma (TRAPP). In addition, primary cutaneous angioplasmacellular hyperplasia (PCAH) overlaps with these other 3 conditions. We intend to study the expression of peripheral node addressins in PLP, APACHE, TRAPP, and PCAH. We studied 1 case of PLP, 2 cases of APACHE, 2 cases of TRAPP, and 2 cases of PCAH. Immunostainings for MECA-79 and WT-1 were obtained in all cases. All cases showed a dense lymphohistiocytic dermal inflammatory infiltrate with abundant plasma cells. In addition, HEV were prominent in all cases. Cases of PLP, APACHE, and TRAPP expressed MECA-1. Cases of PCAH did not express MECA-1. Although PLP, APACHE, and TRAPP seem to fall under the same morphologic spectrum with different clinical representations, PCAH seems to be a different entity, with histopathologic peculiarities and a different immunophenotype.

Cutaneous Angiolymphoid Hyperplasia in a Dog

A 5-year-old male miniature dachshund was presented with a dermal nodule on the left forelimb that increased to 5 mm in diameter over a 2-month period. Grossly, the nodule was firm, and both the external and cut surfaces were homogeneously pale pink in colour. Microscopically, the nodule was comprised of mainly plump endothelial cells and inflammatory cells; among the latter, lymphocytes were predominant, with few scattered plasma cells, mast cells and macrophages. Lymphoid follicles with germinal centres were often observed. Mitotic figures were not observed amongst the endothelial cells. Immunohistochemically, the endothelial cells were positive for vimentin, factor VIII-related antigen and CD31, and the surrounding cells were positive for smooth muscle actin. Lymphocytes expressed CD3 or BLA36. These findings led to a diagnosis of cutaneous angiolymphoid hyperplasia. To the best of our knowledge, this is the first report of a cutaneous proliferative disorder comprising an admixture of proliferating vascular endothelial cells and lymphocytic infiltration with follicle formation in a dog.

Acral angiokeratoma-like pseudolymphoma in a middle-aged woman

Acral angiokeratoma-like pseudolymphoma is a rare type of pseudolymphoma presenting as dark-red papules on the hand or foot. We describe a 59-year-old woman who presented with an unusual unilateral, clustered aggregate of scaly violaceous papules on the toe with an indolent course. Skin biopsy showed a prominent vascular proliferation associated with a dermal infiltrate of monoclonally rearranged T-follicular helper phenotype T-cells, in keeping with CD4+ small/medium T-cell lymphoproliferative disorder (SMPTC-LPD). Based on the unique clinical morphology, distribution of the lesions and dermoscopic appearance, a clinicopathologic diagnosis of acral angiokeratoma-like pseudolymphoma was favored. This case demonstrates the importance of clinicopathological correlation in such diagnostically challenging patients who present with overlapping features on the spectrum of pseudolymphoma and cutaneous T-cell lymphoma.

Cutaneous Pseudolymphomas

The term cutaneous pseudolymphoma refers to benign reactive lymphoid proliferations in the skin that simulate cutaneous lymphomas. It is a purely descriptive term that encompasses various reactive conditions with a varied etiology, pathogenesis, clinical presentation, histology, and behavior. We present a review of the different types of cutaneous pseudolymphoma. To reach a correct diagnosis, it is necessary to contrast clinical, histologic, immunophenotypic, and molecular findings. Even with these data, in some cases only the clinical course will confirm the diagnosis, making follow-up essential.

T-cell rich angiomatoid polypoid pseudolymphoma: a novel cutaneous pseudolymphoma

Cutaneous pseudolymphomas refer to a group of benign reactive T or B cell lymphoproliferative processes that simulate cutaneous lymphomas. T cell rich angiomatoid polypoid pseudo lymphoma (TRAPP) of the skin is a unique form of T cell rich cutaneous pseudolymphoma. A 13-year-girl presented with an asymptomatic skin colored papule on the right elbow, the biopsy of which revealed features consistent with TRAPP. The dermis showed an infiltrate of lymphocytes, plasma cells, and histiocytes along with prominent vascular channels lined by plump endothelium. An immunohistochemical study showed a predominance of T cells over B cells. The morphological and immunohistochemical features pointed towards the diagnosis of TRAPP. We report this rare entity, only 17 cases of which have been described so far in literature. The differential diagnoses have also been discussed.