Abstract
Purpose :
To provide the first genetic, histopathological, immunohistochemical, and clinical characterization of precursor B-cell Lymphoblastic Lymfoma (B-LBL) of the extraocular muscles. First description of an extremely rare cause of orbital lymphoma in adults
Methods :
Multible orbital biopsies from a presumed orbital lymphoma were obtained surgically after magnetic resonance imaging (MRI) showed swelling of the medial and inferior rectus muscles of a 56-year-old male. Routine histopathology, immunohistochemestry, and genetic analysis using fluorescent in situ hybridization (FISH), genome-wide array CGH analysis (a-CGH), multiplex ligation-dependent probe amplification (MLPA), and multiplex RT-PCR was performed. The patient was treated with radiotherapy (2Gy x 20) and chemotherapy according to the NOPHO protocol. Serial blood tests, bone marrow aspirates, orbital MRIs and positron emission tomography was done
Results :
Histopathologically, a lymphocytic infiltrate was seen within skeletal muscle tissue but not in orbital fat. Tumor cells were small and immature and stained strongly for CD10, CD79a, PAX5, and BCL-2. The Ki-67 proliferative index was 90%. MLPA and a-CHG detected whole chromosomal gain of X and 12, and both hemizygous and homozygous deletion on 9p comprising CDKN2A/B. Furthermore, a-CGH detected copy number imbalances consisting of focal or smaller deletions on chromosomes; 1, 9, 10, 11, and 20. No leukemia-associated translocations were identified when screening for 28 chromosomal translocations by multiplex RT-PCR and FISH was negative for ETV-6-break, MLL-rearrangement, and BCR/ABL. Final diagnosis was precursor B-LBL in the periocular muscles. Unfotunately, the patient quickly deteriorated and passed away five months later
Conclusions :
This is the first description of B-LBL in the extraocular muscles and the first genetic characterization. Only seven documented orbital cases in children and young adults exist and this is the oldest patient with B-LBL in the litterature. Orbital B-LBL is extremely rare, may progress quickly in adults and the histopathological diagnosis is challenging to make. It is recommended to obtain material for cytogenetic analysis to support the histopathological diagnosis when orbital biopsies are performed
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.