Author: Dr Ben Tallon, Dermatology Registrar, Greenlane Hospital, Auckland, New Zealand, 2006.
Lymphocytoma cutis is a rare pseudolymphoma that has also been known as ‘cutaneous lymphoid hyperplasia’ or ‘lymphadenosis benigna cutis’. It is a process that simulates a cutaneous lymphoma (blood cell cancer developing in the skin), but it behaves in a harmless manner. It appears to be a reactive process.
The median age of those effected is 34 years old, with males more frequently affected than females by a ratio of 3 to 1. In published studies, typically whites are affected 9 times more commonly than blacks.
Most cases cannot be attributed to any cause, but in some there is an identifiable trigger. These include foreign agents such as:
Lymphocytoma cutis presents as soft, doughy or firm nodules (lumps). These range from skin coloured to red-brown or red-purple in colour, and occasionally have a scale or crust on the surface. They are not usually itchy or sore. They develop on the face in 70% of cases, less commonly on the chest and upper extremities. Single nodules or small numbers of lesions appear 72% of the time, and more numerous lesions are uncommon.
The diagnosis is suggested by the clinical behaviour of the lesion. Typically there is a small solitary lesion, sometimes preceded by a precipitating factor, which does not progress or spontaneously resolves.
Skin biopsy is essential to confirm the benign nature of the lesion. In lymphocytoma cutis, the histology shows a mixture of B and T lymphocytes (inflammatory cells), with benign immunohistochemistry (cell staining). Features favouring a malignant proliferation (lymphoma) include absence of so-called tingible bodies, reduced proliferation rate, positive gene rearrangement and cells that stain with CD10+ and Bcl6+ outside follicles, and Bcl2+ within follicles. It tends to mimic the B cell lymphomas such as follicle centre lymphoma, marginal zone B-cell lymphoma or large B-cell lymphoma.
Some researchers have subtyped the lymphocytoma cutis into B-cell or T-cell, according to which lymphoid cell pattern is present on the biopsy. Further divisions within these groups are largely by its cause, if any is identified. It is not always easy for the pathologist to follow this classification, and many are now included in the larger umbrella term of pseudolymphoma.
Other than distinguishing lymphocytoma cutis from cutaneous lymphoma, it is also important to consider the following as alternative diagnoses:
Specific features seen in the biopsy specimen may be the only way to determine the correct diagnosis in some cases.
The first step is to remove any potential cause or offending agent. Small numbers of cases of lymphocytoma cutis have been reported to respond to the following:
Observation with careful follow-up is a reasonable option.
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