Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Pseudolymphomas of the Skin
Key Points
-
Cutaneous pseudolymphomas are benign inflammatory skin diseases that mimic malignant lymphomas either clinically, histopathologically, or both.
-
Cutaneous pseudolymphomas should be classified precisely according to specific clinicopathologic entities.
-
Integration of clinical, histopathologic, immunophenotypic and molecular genetic features is crucial for the diagnosis of cutaneous pseudolymphomas.
-
Some non-lymphoid malignant neoplasms may simulate histopathologically the picture of a cutaneous lymphoma.
Introduction
Pseudolymphomas of the skin are benign lymphocytic proliferations that simulate cutaneous malignant lymphomas clinically and/or histopathologically. The term pseudolymphoma does not refer to any particular disease but rather to a heterogeneous group of inflammatory conditions and benign ‘tumors’ of diverse causes. For proper treatment, it is important to identify specific entities. In addition to benign inflammatory skin disorders, some non-lymphoid malignant neoplasms may simulate histopathologically the picture of a cutaneous lymphoma.
History and classification
Cutaneous pseudolymphomas have been known for a long time. In recent years, many inflammatory skin diseases have been added to the group of the cutaneous pseudolymphomas, mainly because of the presence of histopathologic features similar to those observed in malignant lymphomas of the skin. Table 20.1 shows a modern clinicopathologic classification of conditions that are currently viewed as cutaneous pseudolymphomas.
Table 20.1
Classification of Cutaneous Pseudolymphomas
| Clinicopathological Entity | Simulated Malignant Lymphoma |
|---|---|
| Actinic reticuloid | Mycosis fungoides/Sézary syndrome |
| Lymphomatoid contact dermatitis | |
| Solitary T-cell pseudolymphoma (superficial type) | |
| Lichenoid (‘lymphomatoid’) keratosis | |
| Lichenoid pigmented purpuric dermatitis (including lichen aureus) | |
| Lichen sclerosus et atrophicus | |
| Vitiligo (inflammatory stages) | |
| Annular lichenoid dermatitis of youth (exact nosology yet unclear) | |
| CD8 + cutaneous infiltrates in HIV-infected patients | |
| Lymphomatoid drug reaction, T-cell type | |
| Pseudolymphomas in tattoos, T-cell type | |
| Pseudolymphomas at sites of vaccination, T-cell type | |
| Mycosis fungoides-like infiltrates in regressing malignant epithelial and melanocytic tumors | |
| Pseudolymphomas in herpes simplex or herpes zoster infections PLEVA, including the febrile ulcero-necrotic variant | Cytotoxic NK/T-cell lymphomas or Lymphomatoid papulosis/cutaneous anaplastic large cell lymphoma |
| Atypical lymphoid infiltrates (CD30) associated with: orf, milker's nodule, molluscum contagiosum and other infectious disorders | Lymphomatoid papulosis/cutaneous anaplastic large cell lymphoma |
| Persistent arthropod bite reactions (including nodular scabies) | |
| Drug eruptions with clusters of CD30 + lymphocytes | |
| Lupus panniculitis | Subcutaneous ‘panniculitis-like’ T-cell lymphoma |
| Lymphocytoma cutis | Follicle center lymphoma Marginal zone B-cell lymphoma Diffuse large B-cell lymphoma |
| Lymphomatoid drug reaction, B-cell type | Follicle center lymphoma |
| Pseudolymphoma after vaccination, B-cell type | |
| Pseudolymphoma in tattoos, B-cell type | Marginal zone B-cell lymphoma |
| Morphea, inflammatory stage | |
| Syphilis (secondary) | |
| ‘Acral pseudolymphomatous angiokeratoma’ (small papular pseudolymphoma) | |
| Inflammatory pseudotumor (plasma cell granuloma) Cutaneous plasmacytosis | Marginal zone B-cell lymphoma, plasmacytic variant |
| Lymphocytic infiltration of the skin (Jessner-Kanof) | Cutaneous manifestations of B-cell chronic lymphocytic leukemia |
| Cutaneous extramedullary hematopoiesis | Cutaneous manifestations of myeloid leukemia |
| Reactive angioendotheliomatosis/Intravascular histiocytosis | Intravascular diffuse large cell lymphoma |
| Benign intravascular proliferation of lymphoid blasts |
Epidemiology
There are no exact data concerning the incidence, prevalence, and geographic distribution of cutaneous pseudolymphomas. Cutaneous pseudolymphomas induced by the spirochetal microorganism Borrelia burgdorferi (i.e. Borrelia lymphocytoma) commonly arise in regions with endemic Borrelia burgdorferi infection.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here
