Immunohistochemical Approach to Genetic Subtyping of Anaplastic Large Cell Lymphoma

Abstract

Anaplastic large cell lymphoma (ALCL) can be classified genetically based on rearrangements (R) of the ALK, TP63, and/or DUSP22 genes. ALK-R defines a specific entity, ALK-positive ALCL, while DUSP22-R and TP63-R define subgroups of ALK-negative ALCLs with distinct clinicopathologic features. ALK-R and TP63-R produce oncogenic fusion proteins that can be detected by immunohistochemistry. ALK immunohistochemistry is an excellent surrogate for ALK-R and screening with p63 immunohistochemistry excludes TP63-R in two third of ALCLs. In contrast, DUSP22-R does not produce a fusion protein and its identification requires fluorescence in situ hybridization. However, DUSP22-R ALCL has a characteristic phenotype including negativity for cytotoxic markers and phospho-STAT3 Y705 . Recently, we also identified overexpression of the LEF1 transcription factor in DUSP22-R ALCL. Here, we sought to validate this finding and examine models for predicting DUSP22-R using immunohistochemistry for LEF1 and TIA1 or phospho-STAT3 Y705 . We evaluated these 3 markers in our original discovery cohort (n = 45) and in an independent validation cohort (n = 46) of ALCLs. The correlation between DUSP22-R and LEF1 expression replicated strongly in the validation cohort (P < 0.0001). In addition, we identified and validated a strategy using LEF1 and TIA1 immunohistochemistry that predicted DUSP22-R with positive and negative predictive values of 100% after exclusion of indeterminate cases and would eliminate the need for fluorescence in situ hybridization in 65% of ALK-negative ALCLs. This approach had similar results in identifying DUSP22-R in the related condition, lymphomatoid papulosis. Together with previous data, these findings support a 4-marker immunohistochemistry algorithm using ALK, LEF1, TIA1, and p63 for genetic subtyping of ALCL.

Constant small‐cell changes and variable LEF1 expression in DUSP22‐rearranged primary cutaneous anaplastic large‐cell lymphoma: Analysis of the repeated biopsies of three patients

“…Regardless of the staining intensity, the results of LEF1 and GrB immunostaining were considered positive when more than 75% and 20% of the tumor cells were stained, respectively. 11 The result of CD30 immunostaining was considered positive when more than 75% of the tumor cells were stained according to the current diagnostic criteria for ALCL. 1 The results of other immunostainings were considered positive when more than 5% of the tumor cells were stained.…”

“…In DUSP22-rearranged ALCL, LEF1 tends to be expressed in >75% of the tumor cells, and cytotoxic markers are typically absent. 8,11 In a previous study, the IHC of LEF1 identified the presence of DUSP22-R with a sensitivity of 93.8% and specificity of 96.0%; however, only seven pcALCLs were included in the study, including one or two with DUSP22-R. 8 Therefore, whether LEF1 IHC is useful for screening DUSP22-rearranged pcALCLs remains unclear.…”

“…7 Therefore, auxiliary methods for screening DUSP22-rearranged pcALCLs have been developed. [8][9][10][11] DUSP22-rearranged pcALCL shows a biphasic pattern, which is not observed in those without DUSP22-R. 2,12 This pattern is characterized by two populations of neoplastic cells, in which medium-to large-sized atypical lymphocytes diffusely infiltrate the dermis and small cells infiltrate the epidermis, resembling pagetoid reticulosis. 1 However, this biphasic pattern has only been reported in 10 patients who developed pcALCL with DUSP22-R. 2,5,10,12,13 Immunohistochemistry (IHC) for the detection of LEF1 and cytotoxic markers is correlated with the diagnosis of DUSP22-R.…”

“…However, FISH analysis is not readily available in all pathology departments and cannot be performed using old formalin‐fixed paraffin‐embedded tissues showing DNA degradation 7 . Therefore, auxiliary methods for screening DUSP22 ‐rearranged pcALCLs have been developed 8–11 …”

“…Immunohistochemistry (IHC) for the detection of LEF1 and cytotoxic markers is correlated with the diagnosis of DUSP22 ‐R. In DUSP22 ‐rearranged ALCL, LEF1 tends to be expressed in >75% of the tumor cells, and cytotoxic markers are typically absent 8,11 . In a previous study, the IHC of LEF1 identified the presence of DUSP22 ‐R with a sensitivity of 93.8% and specificity of 96.0%; however, only seven pcALCLs were included in the study, including one or two with DUSP22 ‐R 8 .…”