In the ALCL group, there were 91 males and 63 females and the mean age was 43 years (4-92 years). A total of 130 cases were S-ALCL, with a nodal presentation in 104 cases (68%) and extranodal presentations in 26 cases (32%), including soft tissue, digestive tract, bone, and breast. Twenty-four cases were primary C-ALCL. Morphologically, most ALCL cases were of the common subtype (97%), with 2 cases of the small cell variant and 3 cases of the lymphohistiocytic variant; all but one of these variants were nodal.
All cases of ALCL were CD30 positive in virtually all neoplastic cells. The immunophenotype was T cell in 92 cases (60%) and null cell in the remaining 62 cases (40%). Nuclear expression of p63 protein was seen in 68 (44%) of 154 cases of ALCL; 35 cases of 1+ (51%), 14 cases of 2+ (21%), and 19 cases of 3+ (28%) (). In the group of S-ALCL, 58 (46%) of 130 cases showed p63 expression, most of them 1+ (53%), the rest were 2+ and 3+ in a similar proportion (). All but 2 p63-positive cases were of common type; one was a small cell variant and the other one was a lymphohistiocytic variant. ALK expression was observed in 49 (38%) of the S-ALCL cases and 20 (41%) of these cases, all nodal, demonstrated expression of p63, mostly 1+ (65%). There was no statistically significant association between p63 expression and ALK-positive or ALK-negative ALCL groups, even when the cases were stratified by phenotype (T or null) ().
Fig. 1 S-ALCL case, common type; A, hematoxylin-eosin (original magnification, ×200); B, CD30 positive (original magnification, ×200); C, CD3 positive, T-cell phenotype (original magnification, ×200); D, p63 nuclear expression (score (more ...)
ALCL p63-positive cases: p63 scores related to anatomical type (S-ALCL and C-ALCL)
Distribution of p63 expression in ALK-positive and ALK-negative-S-ALCL
It is worth mentioning that CD45 was expressed in 91 cases (70%). Twelve (31%) of the 39 cases of CD45-negative ALCL showed p63 expression; 3 of these cases had a null phenotype with no expression of ALK. There was no significant association between p63 and CD45 expression in the S-ALCL group (χ2=4.94 with P = .18) (). Clusterin was expressed in 64 cases (49.2%) of S-ALCL.
p63 distribution in S-ALCL in relation to CD45 expression
C-ALCL presented with a T-cell immunophenotype in 10 cases (42%) and null-cell immunophenotype in 14 cases (58%). As expected, all C-ALCL were negative for ALK expression. p63 expression was observed in 10 cases (46%) of C-ACLC. Only 3 of these cases were CD45 negative, one of them expressing p63. Clusterin positivity was observed in 10 C-ALCL (41.7%) cases, 3 with p63 coexpression.
It was not possible to detect significant differences in p63 expression between C-ALCL and S-ALCL owing to the small number of patients in the C-ALCL group. The χ2 statistic was equal to 2.98 with P = .23 ().
PAX-5 expression was seen in 5 cases of ALCL, including 3 S-ALCL and 2 C-ALCL, all of T-cell phenotype; 3 of these 5 were p63 positive. On the other hand, in the group of 149 PAX-5–negative ALCL cases, 65 (44%) showed expression of p63. CD15 positivity was identified in 3 cases of ALCL; all of them PAX-5/CD20 negative and CD45 positive; one showed a T-cell phenotype and the other 2 were of null type, one of these being p63 positive. The most overlapping cases in reference to the differential diagnosis with CHL included 8 cases of CD45/ALK negative, null phenotype; 3 other cases which were CD15 positive; and 5 cases which were PAX-5 positive; 7 (44%) of these 16 cases showed p63 expression.
In the group of 58 HL cases, 25 were male and 33 female with mean age of 32 years (range, 4 to 82 years). Among the 51 CHL, 39 cases (67%) were nodular sclerosis, 8 cases (16%) mixed cellularity, 1 case lymphocyte depletion, and 3 unclassified. None of the cases of CHL showed p63 expression (). CD30 was expressed in all CHL cases, CD15 expression was present in 45 cases (88%), and 8 cases (16%) expressed CD20. PAX-5 was positive in 34 cases (67%), including 28, which were CD20 negative. In 17 cases of PAX-5–negative CHL, only 2 were CD20 positive and one other case was CD15 negative. All CHL cases were CD45 negative. Clusterin expression was observed in 11 CHL cases (22%). p63 expression was identified in 2 (29%, 1+) of 7 cases of nodular lymphocyte predominance HL; these cases were all CD20 and PAX-5 positive.
Fig. 2 Classical HL; A, hematoxylin-eosin (original magnification, ×200); B, p63 negative in Reed-Sternberg cells and their variants (thick arrows); a few reactive lymphoid cells reveal p63 nuclear expression (thin arrow) (original magnification, ×200). (more ...)
summarizes the immunophenotype results in all cases of ALCL and HL.
Immunohistochemical results in ALCL and CHL