Characteristic features of PCFCL with a diffuse growth pattern and PCDLBCL, LT
| . | PCFCL, diffuse large cell . | PCDLBCL, LT . |
|---|---|---|
| Clinical presentation | Localized skin lesions on head or trunk; multifocal lesions in rare cases | Skin tumors on (lower) leg(s); uncommonly, lesions at other sites than the leg (15%) |
| Histopathology | ||
| Morphology tumor cells | Predominance of large centrocytes; centroblasts may be present, but not in confluent sheets | Predominance or confluent sheets of centroblasts and/or immunoblasts |
| Admixed T cells | Often abundant | Sparse, mainly perivascular |
| Immunohistochemistry | ||
| B-cell lineage markers | CD20+, CD79a+, PAX5+, IgM−, IgD− | CD20+, CD79a+, PAX5+, IgM+, IgD+/−; monotypic light chain expression |
| Germinal center markers | BCL6+, BCL2−, CD10− | BCL6+/−, BCL2+, CD10− |
| Postgerminal center markers | IRF4/MUM1−, FOXP1− | IRF4/MUM1+, FOXP1+ |
| MYC expression | Negative | Positive (65%-80%) |
| CD21/CD35: (remnants) of FDC networks | Sometimes present | Absent |
| Molecular genetics | ||
| Gene expression profile | GCB-type DLBCL | ABC-type DLBCL |
| Translocations BCL6, MYC, IgH | Absent | BCL6 (30%), MYC (35%), IgH (50%) |
| Array-based CGH; FISH | Amplification 2p16.1 Deletion 1p36 Deletion 14q11.2-q12 | Deletion 6q arm (BLIMP1:60%) Deletion 9p21.3 (CDKN2A:67%) |
| NF-κB pathway mutations | No MYD88 mutation | MYD88 (60%), CD79B (20%), CARD11 (10%), TNFAIP3/A20 (40%), |
| Treatment and clinical course | ||
| First line of therapy | Radiotherapy | R-CHOP |
| Relapse rate | 30% | 70% |
| Extracutaneous dissemination | 10% | 45% |
| Prognosis | 5-y survival, 95% | 5-y survival, 50%-60% |
| . | PCFCL, diffuse large cell . | PCDLBCL, LT . |
|---|---|---|
| Clinical presentation | Localized skin lesions on head or trunk; multifocal lesions in rare cases | Skin tumors on (lower) leg(s); uncommonly, lesions at other sites than the leg (15%) |
| Histopathology | ||
| Morphology tumor cells | Predominance of large centrocytes; centroblasts may be present, but not in confluent sheets | Predominance or confluent sheets of centroblasts and/or immunoblasts |
| Admixed T cells | Often abundant | Sparse, mainly perivascular |
| Immunohistochemistry | ||
| B-cell lineage markers | CD20+, CD79a+, PAX5+, IgM−, IgD− | CD20+, CD79a+, PAX5+, IgM+, IgD+/−; monotypic light chain expression |
| Germinal center markers | BCL6+, BCL2−, CD10− | BCL6+/−, BCL2+, CD10− |
| Postgerminal center markers | IRF4/MUM1−, FOXP1− | IRF4/MUM1+, FOXP1+ |
| MYC expression | Negative | Positive (65%-80%) |
| CD21/CD35: (remnants) of FDC networks | Sometimes present | Absent |
| Molecular genetics | ||
| Gene expression profile | GCB-type DLBCL | ABC-type DLBCL |
| Translocations BCL6, MYC, IgH | Absent | BCL6 (30%), MYC (35%), IgH (50%) |
| Array-based CGH; FISH | Amplification 2p16.1 Deletion 1p36 Deletion 14q11.2-q12 | Deletion 6q arm (BLIMP1:60%) Deletion 9p21.3 (CDKN2A:67%) |
| NF-κB pathway mutations | No MYD88 mutation | MYD88 (60%), CD79B (20%), CARD11 (10%), TNFAIP3/A20 (40%), |
| Treatment and clinical course | ||
| First line of therapy | Radiotherapy | R-CHOP |
| Relapse rate | 30% | 70% |
| Extracutaneous dissemination | 10% | 45% |
| Prognosis | 5-y survival, 95% | 5-y survival, 50%-60% |
CGH, comparative genomic hybridization; FDC, follicular dendritic cell; FISH, fluorescence in situ hybridization; R-CHOP, rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisone.