Sclerosis in diffuse histiocytic lymphoma: a clinicopathologic study of 25 cases

Sclerosis was observed in the lymph node specimens of 26 of 57 (46%) patients with diffuse histiocytic lymphoma. Two major types of sclerosis was observed: "compartmentalizing" (56%), in which the tumor was divided into many small compartments by anastomosing, hyalinized stroma; and "diffuse" (44%), in which the sclerosis occurred without evident partitioning of the tumor. The hyalinized stroma of the compartmentalizing sclerosis was frequently continuous with small vessels accompanied by aggregates of small lymphocytes, suggesting that the sclerosis was related to the occurrence of small lymphocyte-associated postcapillary venules. Compartmentalizing sclerosis was further divided into two groups: The first group (even pattern) was characterized by an orderly occurrence of the stromal network with no evidence of distortion, evenly spaced tumor cells showing no axis in their arrangement, and a sharp demarcation of tumor cells from the stroma. The second group (uneven pattern) was marked by either a disorderly occurrence of the stromal network with distortion of the overall pattern, tumor cells arranged along an axis, or poor demarcation of tumor cells from the stroma with individual envelopment of tumor cells by the stroma. Approximately two-thirds of the patients (9/14) with the compartmentalizing sclerosis survived two years or more after diagnosis; most patients (10/11) with diffuse sclerosis died within two years. Compartmentalizing sclerosis, even pattern, was associated with a consistently favorable prognosis; the uneven pattern was not. This study indicates a marked variation in the survival of patients with diffuse histiocytic lymphoma with sclerosis and demonstrates that prognostic subgroups may be delineated by additional morphologic features.