Primary cutaneous B-cell lymphoma in a child.

Primary cutaneous B-cell lymphoma is a B-cell lymphoma of the skin with no evidence of extracutaneous involvement at the time of diagnosis. In this report, we describe an 8-year-old boy who presented with a firm, alopecic, skin-colored, smooth nodule over the right frontal scalp. Histological examination revealed a mid-to deep-dermal mononuclear lesion. Immunohistochemical staining revealed a B-cell population that was CD10(+), CD5(-), CD21(+), and bcl2(-). This pattern of reactivity is characteristic of primary cutaneous B-cell lymphoma of follicle-center subtype. To the best of our knowledge, this is the first report of this type of cutaneous lymphoma in a child.