CD8+ epidermotropic cytotoxic T-cell lymphoma with peripheral blood and central nervous system involvement

Most cutaneous T-cell lymphomas demonstrate a malignant population with a CD4(+) phenotype. In rare cases, CD8(+) phenotypes have been described based on immunostaining of skin specimens. Although some CD8(+) lymphomas have an indolent course, others, such as CD8(+) epidermotropic cytotoxic T-cell lymphomas, are typically more aggressive. To our knowledge, involvement of peripheral blood or cerebrospinal fluid with a malignant population of CD8(+) cells demonstrated by flow cytometry and T-cell receptor gene rearrangement has not been previously described.

We describe a patient with a CD8(+) cutaneous T-cell lymphoma with an initially indolent course and early stage diagnosed on the basis of a skin biopsy specimen. However, when flow cytometry was performed looking specifically at CD8(+)/CD4(-) cells in the peripheral blood and cerebrospinal fluid, a malignant population of CD8(+)/CD4(-)/CD26(-)/CD7(-) cells was discovered.

It is important for prognosis and treatment to be able to identify CD8(+) epidermotropic cytotoxic T-cell lymphoma and separate it from other relatively indolent CD8(+) lymphomas. Furthermore, detection of an abnormal CD8(+)/CD26(-)/CD7(-) T-cell population within the peripheral blood has important prognostic and therapeutic implications. The use of flow cytometry looking for abnormal CD8(+) populations in the peripheral blood or cerebrospinal fluid can assist with this critical information.