Role of apoptosis in spontaneous regression of peripheral T-cell lymphoma arising in the skin or subcutis.

Apoptosis was suspected to play a significant role in spontaneous regression of skin lesions in four cases of peripheral T-cell lymphoma arising in the skin or subcutis. All of the patients had skin tumors with ulcer formation, but no metastasis to the lymph nodes or viscera. Biopsy showed a sea of CD3-positive lymphoma cells involving the dermis to the subcutis with scattered foci of coagulative necrosis. In the zone of incipient necrosis surrounding the core of coagulative necrosis, frequent apoptotic bodies were identified by electron microscopy (EM), and DNA strand breaks were detected in 34% to 51% (mean, 42%) of lymphoma cells by the TdT-mediated deoxyuridine triphosphate (dUTP)-biotin nick end-labeling (TUNEL). As for the pathogenesis of coagulative necrosis, ischemic necrosis attributable to lymphocytic vasculitis appeared unlikely, because necrotic foci were devoid of neutrophils and had no relation to vascular distribution. Primary cataclysmic apoptosis appeared more likely, but its pathogenetic role could not be established, because EM and TUNEL could not be applied to the core of the debris-ridden coagulative necrosis. Although these cases had been classified as pseudolymphomas because they were histologically malignant but clinically benign, they were in fact true lymphomas characterized by extensive coagulative necrosis with a high rate of apoptosis demonstrable in the zone of incipient necrosis.

Cytogenetic findings in peripheral T-cell lymphomas as a basis for distinguishing low-grade and high-grade lymphomas.

Cytogenetic studies on lymph node and skin biopsy specimens and peripheral blood in 104 patients with peripheral T-cell lymphomas (PTL) were compared with histopathologic diagnoses made according to the updated Kiel classification. Low-grade lymphomas presented normal metaphases more frequently than high-grade ones (P < .0001). This difference remained significant if cases with greater than 10% and greater than 50% normal metaphases in unstimulated cultures and in cultures stimulated by different mitogens were compared. On the other hand, high-grade lymphomas more often showed aberrant clones (P < .05), triploid to tetraploid clones (P < .0001), and complex clones with more than four chromosome changes (P < .01). Low-grade PTL showed consistent cytogenetic features. Clones with both inv(14)(q11q32.1) and trisomy 8q, mostly caused by i(8q)(q10), were found in all cases of T-cell chronic lymphocytic leukemia (T-CLL) and T-cell prolymphocytic leukemia (T-PLL). Trisomy 3 was observed only in angioimmunoblastic lymphadenopathy with dysproteinemia (AILD)-type PTL, T-zone lymphoma, and lymphoepithelioid lymphoma. Moreover, the proportion of normal metaphases in these PTL was higher than in the other low-grade PTL (P < .01). On the contrary, T-CLL, T-PLL, and cutaneous T-cell lymphomas (CTCL) showed complex clones (P < .0001), duplications in 6p (P < .01), deletions in 6q (P < .01), trisomy 8q (P < .00001), inv(14) (P < .00001), and monosomy 13 or changes of 13q14 (P < .001) more frequently than the other low-grade PTL. Trisomy 5 and + X predominated in AILD-type PTL. A cytogenetic feature characteristic of AILD-type PTL and CTCL was unrelated clones, which were found in 15% of AILD-type PTL and 17% of CTCL. The only chromosome aberration restricted to a certain high-grade PTL was t(2;5)(p23;q35) in large-cell anaplastic lymphoma. Deletions in 6q, total or partial trisomies of 7q, and monosomy 13 or changes of 13q14 turned out to be significantly more frequent in high-grade than in low-grade lymphomas (P < .01, P < .01, and P < .05, respectively). In summary, the cytogenetic findings in our series of 104 PTL enabled us to distinguish not only between low-grade and high-grade lymphomas but also between various entities of PTL. Thus, the cytogenetic findings paralleled the histopathologic diagnoses made according to the updated Kiel classification.

Cutaneous T cell lymphoma of signet ring cell type: a specific clinico-pathologic entity.

We describe a new case of signet ring cell peripheral T cell lymphoma in a 45-year-old man. This lymphoma had a very indolent course, since--without treatment--the clinical staging has shown no evidence of disease progression 11 years after initial symptoms. Immunophenotype indicated pan T antigens (Leu 4 CD3, Leu 1 CD5) and T suppressor cytotoxic antigen (IOT8 CD8) expression. Several T antigens (Leu 5b CD2, Leu 9 CD7, Leu 3a CD4) were not expressed. The proliferation index was less than 5% with Ki 67 monoclonal antibodies. The ultrastructural study showed characteristic cytoplasmic vacuoles containing microvesicles. Five cases of signet ring T cell lymphoma, which were very similar to our case, have been previously described. Their characteristics were primary cutaneous presentation, indolent course, good response to current therapies and a long survival period. The indolent course of these signet ring cell lymphomas may indicate that this type of lymphoma is a low grade malignant lymphoma and not only a morphological pattern.

[Midline peripheral T-cell lymphoma--an immunohistochemical and electron microscopy study].

Twenty-six cases of nasal/nasopharyngeal midline peripheral T-cell lymphomas were studied clinically and pathologically with immunohistochemical markers and electronmicroscopy. A clearer understanding of the nature of midline malignant reticulosis has obtained. Immunohistochemical markers confirmed that except 5 small specimens which failed to show the monoclonal growth, 18 cases had peripheral T-cell lymphomas, 15 had TH, 3 Ts and 2 B-Cell lambda light chain and 1 HC. Morphological observations showed that 24 cases out of 26 exhibited middle and small polymorphic T-cells. This tumor had distinctive clinical features and was characterized by midfacial progressive necrosis, slow growth, local invasion and rarely metastasis, often with prominent granulomatous and vascular proliferation. Therefore, a discrimination of this disease from midline malignant reticulosis and midfacial destructive lesions is absolutely necessary.