eMedicine Specialties > Dermatology > Lymphoma and Related Processes

Pseudolymphoma, Cutaneous

Author: Christine J Ko, MD, Assistant Professor, Departments of Dermatology and Pathology, Yale University School of Medicine
Coauthor(s): Jon H Meyerle, MD, Assistant Professor, Department of Dermatology, Johns Hopkins University School of Medicine; Consulting Staff, Laboratory Director, Department of Dermatology, Walter Reed Army Medical Center and National Naval Medical Center; Earl J Glusac, MD, Professor, Departments of Pathology and Dermatology, Yale University School of Medicine
Contributor Information and Disclosures

Updated: Oct 22, 2008

Introduction

Background

Pseudolymphoma is not a specific disease but rather an inflammatory response to known or unknown stimuli that results in a lymphomatous-appearing but benign accumulation of inflammatory cells.¹ Resemblance to lymphoma is usually most apparent histologically, but some examples may also mimic lymphoma clinically. When known, the inciting agent should be included within the diagnosis. The term pseudolymphoma without modification should be reserved for idiopathic cases.

Localized, nodular pseudolymphomas are more common and typically mimic B-cell lymphoma (for further discussion, see Lymphocytoma Cutis). A variety of specific diseases are sometimes referred to as pseudolymphomas simply because they may resemble lymphoma. These disorders often show broad patches and plaques and often mimic cutaneous T-cell lymphoma. Examples include actinic reticuloid, lymphomatoid contact dermatitis, and lymphomatoid drug eruptions² (see Media Files 2-3).

The Medscape Skin Cancer Resource Center may be of interest.

Pathophysiology

In persons with pseudolymphoma, lymphocytes and other inflammatory cells are recruited to the skin in response to known or unknown stimuli. Most cases are idiopathic. Cases with known etiology include reactions to tattoo dyes, jewelry (especially gold), insect bites, medications,³ folliculitis, trauma, infections, vaccinations,⁴ and contactants. A discrete subset of pseudolymphoma, borrelial lymphocytoma, primarily occurs in Europe in areas endemic for the tick Ixodes ricinus. It is a response to infection by Borrelia burgdorferi subsp afzelius conferred by a tick bite. Another subset of pseudolymphoma is the result of an unusual systemic response to medications, typically anticonvulsants (see Drug-Induced Pseudolymphoma Syndrome).

Frequency

International

No frequency data are available; the condition is uncommon but not rare.

Mortality/Morbidity

Pseudolymphoma is not associated with mortality. Localized variants rarely result in morbidity other than minor pain or pruritus. Rare cases have been described in which pseudolymphoma has evolved into cutaneous lymphoma.

Race

Although 90% of reported patients with pseudolymphoma are white, racial predilection has not been established.

Sex

In reported cases of localized pseudolymphoma, the female-to-male ratio is approximately 2:1. No significant epidemiologic data are available regarding entities in the T-cell pattern pseudolymphoma spectrum.

Age

Individuals of any age may be affected, but localized, nodular pseudolymphoma is most common in early life. The mean age of onset is 34 years. Two thirds of patients are younger than 40 years at the time of biopsy. Approximately 8% of cases involve patients younger than 18 years. Borrelial pseudolymphoma is more common in children than in adults.

Clinical

History

• Patients with B-cell pattern pseudolymphoma present with complaints of a nodule or a group of discrete nodules, usually with minimal associated symptoms.
• Occasionally, cases present with pruritus or pain.
• Patients with T-cell pattern disease usually present with broader patches, which are often symptomatic.

Physical

• Examination of patients with B-cell pattern pseudolymphoma usually reveals a single nodule, from one to several centimeters in diameter. Although the lesions may be soft, they are more often firm. Typically, the lesions are red to purple in color, but they may show no coloration. Approximately three quarters of cases are localized. The remaining cases usually show grouped papules in a single defined region. More disseminated cases are rare. The most common site of involvement is the face (70%) followed by the chest and the upper extremities. Lesions are infrequent below the waist.
• Sites of predilection for borrelial pseudolymphoma include the earlobe, the nipple, the areola, the nose, and the scrotum (sites of low skin temperature).
• Patients with T-cell pattern pseudolymphoma typically present with broad, erythematous patches and/or plaques (see Media File 1). Pseudolymphomatous actinic reticuloid affects sun-exposed areas. Lymphomatoid contact dermatitis demonstrates lesions in areas where the inciting agent has come in contact with the skin.⁵

Causes

Most cases are idiopathic. Known inciting agents include tattoo dyes, jewelry (eg, gold earrings), insect bites, medications, folliculitis, trauma, vaccinations, irritants, and infection (eg, varicella-zoster virus, Borrelia species, molluscum contagiosum).

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