https://orcid.org/0000-0002-8099-9648
Key Points
Extramedullary plasmacytomas in children and adolescents are localized extranodal diseases of the head-neck area lacking dissemination.
Expression of IgA and lack of genetic aberrations characterize this disease which is curable by surgical resection.
Extramedullary plasmacytomas (EMP) are exceedingly rare in children and adolescents. We describe clinical, pathological and molecular features of 13 patients with EMP in this age group (8 males, 5 females, 3-18 years). EMP presented as localized disease involving the Waldeyer´s ring (n=9), the larynx (n=2), the ocular adnexa (n=1) or epipharynx and conjunctiva simultaneously (n=1). One patient with EMP of the tonsils had concurrent Epstein-Barr-virus infection. 12/13 patients with follow-up information reached sustained complete remissions following surgical resection (median follow-up of 38 months). However, local relapses were observed in three patients. Irradiation was applied in only one patient with laryngeal involvement. Histologically sheets of mature plasma cells with light-chain restriction, low proliferation and mostly expression of IgA (11/13, 92%) were observed. Epstein-Barr-Virus, CD56 and Cyclin-D1 were not detected in the plasma cells. Amyloidosis confined to the lesion was observed in one case. Clonal, mostly productive immunoglobulin gene rearrangements with somatic hypermutation (3.3% to 5.7%) were detectable in all informative cases. Fluorescence in situ hybridization revealed absence of chromosomal abnormalities associated with plasma cell neoplasia (e.g. breaks in IGH, MAF, FGFR3, copy number alterations of 1p32, 1q21, RB1, TP53). Targeted next generation sequencing did not reveal any somatic alterations predicted as pathogenic. We conclude, that EMP in children and adolescents is a plasma cell neoplasia with low malignant potential lacking systemic dissemination that differs clinically and molecularly from adult plasma cell myeloma.
