Cutaneous pseudolymphomas are benign lymphoproliferations that clinically and/or histologically simulate cutaneous lymphomas.
They exhibit a wide range of clinical, histological, and immunophenotypic features and can be triggered by different infectious and non-infectious agents.
Clinicopathological correlation plays an important role in the differentiation from cutaneous lymphomas.
Therapy includes avoidance of exposure to the causative agent, immunomodulating agents or ablative approaches.
The term cutaneous pseudolymphoma refers to a group of skin diseases that can be defined as benign lymphoproliferative processes that clinically and/or histologically simulate cutaneous lymphomas. These diseases differ in their clinical, histologic, and immunophenotypic presentation, and are of different etiologies (Table 120-1).
Table 120-1Spectrum of Cutaneous Pseudolymphoma ||Download (.pdf) Table 120-1 Spectrum of Cutaneous Pseudolymphoma
1. Nodular pseudolymphoma
B-cell pseudolymphoma (PSL)
Infections: Borrelia burgdorferi
Drugs: Anticonvulsants, vaccines
Arthropod bites, infestations, leeches (Hirudo medicinalis)
Lymphomatoid reaction to tattoo and metals
2. PSLs—histologic simulators of mycosis fungoides (“pseudo-MF”)
Lymphomatoid contact dermatitis
Lymphomatoid drug reaction
Immunodeficiency-associated cutaneous CD8+ infiltrates
B. burgdorferi–associated T-cell infiltrates
3. Other disorders with lymphocyte-rich infiltrates
Acral persistent angiokeratoma
Cutaneous inflammatory pseudotumor
Angiolymphoid hyperplasia with eosinophilia
T-cell–rich angiomatoid polypoid pseudolymphoma of the skin
Lymphocytic infiltration of the skin
Palpable arciforme migratory erythema
Lichen sclerosus, pityriasis lichenoides, vitiligo
Pigmented purpuric dermatoses
Morphea (inflammatory stage)
Lupus tumidus, lupus panniculitis
4. Benign intravascular proliferation of lymphocytes
Benign intravascular proliferation of lymphoid blasts
Benign atypical intravascular CD30+ T-cell proliferation
A broad spectrum of causative factors known to induce cutaneous pseudolymphomas (PSLs) have been identified. Infectious agents, such as spirochetal bacteria (Borrelia burgdorferi sp., Treponema pallidum), viruses (eg, parapoxviruses), infestations (eg, scabies), insect bites, injection of vaccines or antigens for hyposensitization, foreign bodies such as tattoos and metals, and drugs have been identified as causative factors for PSL. All cases without identifiable cause are referred to as an idiopathic form of PSL.
Various synonyms have been introduced and several terms are still nowadays used to describe PSLs of the skin. For the first time the concept of PSL (pseudomalignancy) had been introduced by M. Kaposi in 1891 (Table 120-2).1 In 1923, Biberstein coined the term lymphocytoma cutis.2 Subsequently, in 1943, Bäfverstedt used the designation lymphadenosis benigna cutis.3 Lever introduced the term pseudolymphoma of Spiegler and Fendt in 1967, and in 1969, Caro and Helwig employed the term cutaneous lymphoid hyperplasia.4 Many other terms were proposed and referred mostly to B-cell PSLs. Among T-cell PSLs, actinic reticuloid was first described in 1969.5 In the 1980s the designation cutaneous PSL for B-cell–dominated and T-cell–dominated processes became more widely ...