Marginal zone B-cell lymphoma in children and young adults

Abstract

We describe the clinicopathologic findings of 48 cases of marginal zone B-cell lymphoma (MZL) in children and young adults, a disease that has been recognized previously only rarely in this age group. Patients ranged in age from 2 to 29 years, with pediatric patients (< or =18 years) comprising 52% of the cases. As in adults, both primary nodal (N) and extranodal (E) MZL were observed. However, primary NMZL comprised the majority of the cases (67%) and demonstrated distinctive clinical and histologic features. NMZL occurred most commonly in young males (median 16 years, male/female ratio 5.4:1), with no underlying disease, presenting as localized adenopathy (90% stage I), with excellent prognosis and low rate of recurrence. In contrast, EMZL were much less common, and patients were older (median 24.5 years), with only a slight male predominance (male/female ratio 1.2:1). Most patients had localized disease (73% stage I) with excellent prognosis and infrequent recurrences. In addition, an association with autoimmune disease was observed in 19% of the EMZL. Both primary NMZL and EMZL in young patients shared similar morphologic and immunophenotypic findings to those described in adults and were monoclonal B-cell proliferations with monoclonality demonstrated in 94% of the cases. A common morphologic feature in NMZL was disruption of residual follicles resembling progressive transformation of germinal centers (PTGC), observed in 66% of the cases. Although the precise relationship of primary NMZL and the PTGC-like changes is unclear, it is possible that NMZL arises in a background of PTGC, as florid PTGC often occurs in young males. We conclude that EMZL in children and young adults are similar to EMZL of mucosa-associated lymphoma tissue occurring in older patients. However, pediatric NMZL appear to have distinctive clinical and histologic features.

FIG. 1.

Clinical manifestations of extranodal marginal zone lymphoma (EMZL) in a 22-year-old man with enlarging conjunctival mass of 6 months’ duration that was excised but recurred rapidly (case no. 2).

FIG. 2.

Histologic and immunophenotypic features of nodal marginal zone lymphoma (NMZL). (A) Lymph node showing partial architectural effacement by marginal zone expansion. Residual follicles are present with small germinal centers and preserved mantle zones. (B) The cells are composed of a polymorphic population of centrocyte-like cells, plasma cells, and scattered larger cells. (C) Hyperplastic follicles with attenuated to absent mantle zones blend imperceptibly with expanded marginal zones. (D) Expanded residual follicles showing PTGC-like changes. (E) IgD immunohistochemical stain highlights disrupted mantle zones resembling PTGC. (F) Immunohistochemical stain with CD20 stains residual follicles and sheets of B cells in the interfollicular areas (E and F, ABC immunoperoxidase, hematoxylin counterstain).

FIG. 3.

Histologic and immunophenotypic features of extranodal marginal zone lymphoma (EMZL). (A) Section of parotid gland showing lymphoepithelial lesion. The epithelium is infiltrated by monocytoid cells. (B) Secondary lymph node involvement by EMZL with multiple clusters of monocytoid cells within dilated sinusoids. (C) The monocytoid cells are composed of medium-sized cells with abundant cytoplasm and indented nuclei. (D) Section of orbital mass with expansion of the marginal zone and infiltration into muscle. The cells show marked plasmacytic differentiation (inset). (E) CD20 highlights a residual germinal center with the plasmacytoid cells showing light chain restriction with lambda stain (F) (E and F, ABC immunoperoxidase, hematoxylin counterstain).

FIG. 4.

Polyacrylamide gel electrophoresis of FR3-IgH PCR showing three bands of similar molecular weight in three separate biopsies of the gastric EMZL (case no. 14). P, patient; MW, molecular weight.