Composite Lymphoma: A Late Relapsing Primary Cutaneous B Cell Lymphoma Coexisting with Nodal Hodgkin’s Lymphoma.
Authors: Pulini Stefano , Angrilli Francesco , Falorio Simona , Fioritoni Giuseppe 
Published: November 2019

Abstract
The simultaneous manifestation of different lymphomas in the same patient or in the same tissue is defined composite lymphoma. Although reports of synchronous or metachronous Hodgkin’s lymphoma (HL) and Non Hodgkin’s lymphoma (NHL) are not uncommon in the literature, the biologic relationship of the 2 malignancies is often unclear. Primary cutaneous B-cell lymphomas (pCBCLs) have been recognized as distinct clinicopathologic entities; they represent a wide spectrum of lymphoproliferative disorders separated from of B-cell NHL secondarily involving the skin and cutaneous B-cell pseudolymphomas. As regarding pCBCLs, a concomitant diagnosis of HL has been described very rarely. This is the case of a caucasian man affected by primary cutaneous follicolar B cell lymphoma (pCFCL). He presented grouped red plaques located on the nape, abdomen, shoulders, arms and even some little tumors surrounded by erythematous papules. Complete staging procedures did show no evidence of extracutaneous disease. A subcutaneous interferon therapy was started, in some months the patient reached a complete remission, and a maintainance therapy was continued for about 2 years. After 15 years, at the age of 58, the patient presented a red to violaceous infiltrated solitary plaque on the back, appeared about 2 months before. The lesion was completely excised and the biopsy showed a diffuse dermal infiltrate, not involving the epidermis, structured in follicle with reactive germinal centers; they were surrounded by small sized monomorphic lymphocytes with irregular nuclei and pale cytoplasm, showing the following immunophenotype pattern: CD20+, CD3−, IRTA+, CD10−, BCL6−, BCL2+, low proliferative index. A plasmacellullar CD138+ and CD79a+ population was at the periphery of the infiltrates, with monotypic expression of cytoplasmic k chain. The whole picture was interpreted as primary cutaneous marginal zone B-cell lymphoma (pCMZL). The association with Borrelia burgdorferi infection, sometimes described in pCMZL, wasn’t demonstrated. The patient presented a large right axillary lymph node that was excised and found to be unexpectly infiltrated by HL, mixed cellularity subtype. The patient underwent a standard baseline staging procedure with total body CT scan and bone marrow trephine biopsy; the latter resulted negative; the t(11;14) and t(14;18) rearrangements weren’t demonstrated in bone marrow; the CT did show no other suspected masses nor lymphoadenopathy, besides the clinically evident right axillary lymph node. A 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) revealed sites of hyperactivity in the same right axillary region, but extending to the subclavian region and the thoracic region. The patient started chemoterapy (ABVD regimen), and at the end of 4 courses a whole body CT scan and FDG-PET resulted both negative. Now he is being treated with radiotherapy. If the nodal malignancy would have been diagnosed first, the skin lesion probably could have been misinterpreted as a secondary localization of HL; if the node biopsy wouldn’t have been performed we could diagnose B-cell NHL secondarily involving the skin (stage IV). Nevertheless the cutaneous and nodal infiltrates had a completely different general picture and phenotype. This case probably reflects a HL after 15-year remission of a pCBCL of low grade and the relationship between HL and the preceding pCFCL is not clear: casual or related to genetic predisposition for oncogenic events or favoured by an immunodeficiency state related to the first disease and the previous immunomodulatory therapy.