Comparison of distinctive clinicopathologic and genetic features in follicular lymphoma subtypes
| . | Usual systemic FL % (n/group total)* . | Cutaneous FL, systemic % (n/group total)† . | Cutaneous FL, skin restricted % (n/group total)‡ . | Pediatric type nodal FL % (n/group total)* . |
|---|---|---|---|---|
| BCL2 rearrangement | 89 (16/18) | 92 (12/13) | 8 (2/26) | 0 (0/26) |
| Mutations in 2 or more of 4 chromatin modifiers (CREBBP, KMT2D, EZH2, and EP300) | 63 (47/75) | 63 (5/8) | 6 (1/16) | 4 (1/24) |
| Ki-67 <30% | 67 (10/15) | 86 (12/14) | 10 (2/20) | 0 (0/26) |
| Clinical | ||||
| Multisystemic involvement | Yes, often widely disseminated | Yes, skin+LNs and/or other organs | No, limited to the skin | No, limited to LNs of 1 area |
| Anatomical location | Variable | Head and neck skin predominant | Head and neck skin predominant | Head and neck LN predominant |
| Therapy | Often requires systemic therapy | Often requires systemic therapy | Localized therapy (excision, targeted RT, IL steroids or IL rituximab) | Localized therapy (excision, targeted RT) |
| Presumed site of disease/clone origin | Bone marrow precursor | Bone marrow precursor | Site of anatomically restricted disease | Site of anatomically restricted disease |
| . | Usual systemic FL % (n/group total)* . | Cutaneous FL, systemic % (n/group total)† . | Cutaneous FL, skin restricted % (n/group total)‡ . | Pediatric type nodal FL % (n/group total)* . |
|---|---|---|---|---|
| BCL2 rearrangement | 89 (16/18) | 92 (12/13) | 8 (2/26) | 0 (0/26) |
| Mutations in 2 or more of 4 chromatin modifiers (CREBBP, KMT2D, EZH2, and EP300) | 63 (47/75) | 63 (5/8) | 6 (1/16) | 4 (1/24) |
| Ki-67 <30% | 67 (10/15) | 86 (12/14) | 10 (2/20) | 0 (0/26) |
| Clinical | ||||
| Multisystemic involvement | Yes, often widely disseminated | Yes, skin+LNs and/or other organs | No, limited to the skin | No, limited to LNs of 1 area |
| Anatomical location | Variable | Head and neck skin predominant | Head and neck skin predominant | Head and neck LN predominant |
| Therapy | Often requires systemic therapy | Often requires systemic therapy | Localized therapy (excision, targeted RT, IL steroids or IL rituximab) | Localized therapy (excision, targeted RT) |
| Presumed site of disease/clone origin | Bone marrow precursor | Bone marrow precursor | Site of anatomically restricted disease | Site of anatomically restricted disease |
IL, intralesional; LN, lymph nodes; RT, radiotherapy.
Based on data from Louissaint et al26 and Green et al.53
Cutaneous FL, systemic (n = 14) includes all cutaneous FL with systemic involvement, including cases of SCFL (n = 10) and PCFCL (systemic spread) (n = 4).
Cutaneous FL, skin restricted (n = 26) includes all cutaneous FL that remain restricted to skin, including PCFCL (skin restricted) but not PCFCL (systemic spread) (n = 4). These data are in contrast to Table 1, which includes all cases of PCFCL (n = 30).