Thymic mucosa-associated lymphoid tissue lymphoma in an adolescent girl

[True thymic hyperplasia : Differential diagnosis of thymic mass lesions in neonates and children]

Reactive and neoplastic thymic pathologies are the main considerations in the case of masses in the anterior and middle part of the mediastinum, while neurogenic tumors are predominant in the posterior mediastinum (which are not dealt with here). In neonates and infants, the commonest pathologies in the anterior mediastinum comprise germ cell tumors (mainly teratomas), congenital thymic cysts and true thymic hyperplasia (TTH). In toddlers, teratomas, yolk sac tumors and cysts predominate. In children over 5 years of age, lymphomas are the commonest mass lesions whereas thymomas and thymic carcinomas are rare. In addition, inflammation-linked hyperplasia in myasthenia gravis and rebound thymic hyperplasia after chemotherapy must be considered. Although rare at all ages, sarcomas must be considered in the differential diagnosis from birth onwards and throughout adolescence. Based on the report of a rare case of recurrent TTH, the differential diagnosis of this benign but potentially life-threatening condition is discussed.

Thymic Extranodal Marginal Zone Lymphoma of Mucosa-associated Lymphoid Tissue with 8q24 Abnormality

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) of the thymus is reported to have characteristic features that distinguish it from MALT lymphoma of other organs; it is proposed to be a distinct clinicopathological subgroup of MALT lymphoma. We herein present a case of thymic MALT lymphoma accompanied by Sjögren's syndrome, involving the first report of a thymic MALT lymphoma patient carrying a chromosomal abnormality of 8q24. No c-myc gene translocation or c-Myc protein overexpression was observed, suggesting that c-myc was not involved in lymphomagenesis or progression. Although we did not examine the mechanisms by which the lymphoma developed, this chromosomal structural change in 8q24 may be associated with the pathogenesis in our case.

Pediatric Pharyngeal IgD-positive Monoclonal Plasmacytoid and Plasma Cell Neoplasm

Pediatric neoplasm with monoclonal proliferation of lymphoplasmacytoid lymphocytes and plasma cells is exceedingly rare and has essentially never been reported in immunocompetent children. Here, we report a previously healthy 13-year-old girl with a pharyngeal mass and enlarged cervical lymph nodes. The pharyngeal mass was composed of CD138, CD79a, MUM-1, IgD, CD20, PAX-5, CD43, λ-restricted monoclonal plasmacytoid, and plasma cells. Scattered CD20, PAX-5 B cells were present in the background. The patient was treated as localized non-Hodgkin lymphoma (stage II) with cyclophosphamide, doxorubicin, vincristine, and prednisone and is in complete remission at 17 months from the last chemotherapy.

A unique description of stage IV extranodal marginal zone lymphoma (EMZL) in an adolescent associated with gamma heavy chain disease

Extranodal Marginal zone lymphoma (EMZL) is a rare, usually localized disease in children. Advanced stage EMZL in adults is considered incurable, with prolonged remissions after chemotherapy. Gamma heavy chain disease (γHCD) is a rare disease of adults associated with lympho-proliferative processes with no comparable reports in children. A case of stage-IV EMZL with γHCD in an adolescent is discussed including treatment with Bendamustine plus Rituximab. The patient remains disease free 18 months from diagnosis. This case highlights necessity for careful diagnostic work-up to identify indolent lymphomas in children which may respond to less toxic chemotherapy than used for common pediatric lymphomas.