MYC status in HIV-associated plasmablastic lymphoma: dual-colour CISH, FISH and immunohistochemistry

We utilised chromogenic and fluorescence in-situ hybridisation (CISH and FISH) to evaluate MYC gene copy numbers and rearrangements within HIV-associated plasmablastic lymphomas (PBLs). Thereafter, clinicopathological features were explored retrospectively.

Sixty-seven (n = 67) patients were included and the HIV seropositive status was confirmed in 98% (63 of 64) with a median viral load of 55 587 (IQR 273 582) copies/ml and median CD4 count of 170 (IQR 249) cells/µl. The mean age was 41 ± 10.1 years and females comprised 54%. PBL was documented predominantly at extra-oronasal topographic regions. Starry-sky (SS) appearance was evident in 33% in association with monomorphic morphology (P-value 0.02). c-MYC protein was expressed in 81% and latent EBV infection was detected in 90%. EBER ISH-positive status and MYC rearrangement occurred in 67% of HIV PBL. MYC aberrations included MYC rearrangement (70%), low-level increase in MYC gene copy numbers (43%), concurrent MYC rearrangement and increased MYC gene copy numbers (49%) as well as low-level chromosome 8 polysomy (6%). MYC aberrations in HIV PBLs were significantly associated with SS appearance (P -0.01), monomorphic morphology (P - 0.03), c-MYC protein expression ≥40% (P - 0.03) and mortality (P - 0.03). There was advanced stage (Ann Arbor III/IV) at presentation (77%) and the median overall survival for HIV PBL was 75 days (95% CI 14-136).

Majority of the HIV-associated PBL tumours harbour MYC aberrations. Due to the persistently inferior survival outcome of HIV-associated PBL in the era of antiviral treatment, targeted and/or intensified therapy of oncogenic MYC may need to be explored in future.