Angiocentric immunoproliferative lesions of the skin show lobular panniculitis and are mainly disorders of large granular lymphocytes.

Eleven patients with angiocentric immunoproliferative lesion (AIL) of the skin were studied. Histologically, three patients were grouped into AIL grade II (AIL-II), whereas eight showed angiocentric lymphoma (AIL-III). All the patients' specimens exhibited lobular panniculitis. Infiltrating atypical lymphocytes in nine patients possessed electron-dense membrane bound granules in electron microscopy. Phenotypically, the lymphoid cells in the AIL-II patients were positive for CD3 epsilon; two of these showed a positive reaction to CD2, CD7, and CD8, but lacked natural killer-associated (NKa) antigens CD16, CD56, and CD57. In six AIL-III patients, lymphoma cells were positive for CD2 in all patients, CD56 in five, CD3 epsilon in four, CD7 in four, interleukin-2 beta receptor in four, a pore-forming protein in four, and CD30 in three patients. The remaining two AIL-III patients had B-cell lymphoma. By the Southern blot analysis, three patients with AIL-III showed a rearranged T-cell-receptor beta-gene or a deletion of its germline. The preceding results in nine of 11 patients suggest that abnormal or neoplastic large granular lymphocytes with the characteristics of T and NK cells have an important role in producing the angiocentric/angiodestructive features and lobular panniculitis. Clinically, all three patients with AIL-II and four with AIL-III showed liver dysfunction, cytopenia, and abnormal coagulopathy during the clinical course. Five patients with AIL-III died within 8 months. The histological grading of AIL, patients' age, and limited clinical stage of the disease seem to correlate with response to the treatment and prognosis.