Diagnosis: Trauma-induced secondary cutaneous plasmacytoma (TISP). Microscopic findings and clinical course Findings from histologic examination showed a nodular infiltrate of mature as well as immature plasma cells in the dermis, separated from the epidermis by a grenz zone (Figures 2 and 3). Results of immunohistochemical analysis showed overwhelming λ light chain positivity. The patient was unable to tolerate bortezomib and was not a good candidate for additional radiotherapy. Treatment with doxorubicin had failed, and she died of progressive disease 5 months later. Discussion Primary cutaneous plasmacytoma is a rare B-cell lymphoma that occurs without MM on presentation. One-third of these cases will ultimately progress to generalized MM.1 Secondary cutaneous plasmacytoma (metastatic cutaneous MM) is a cutaneous plasma cell infiltrate that most commonly occurs, spontaneously, as a local extension of MM from underlying bone.1 In rare cases, lesions of secondary cutaneous plasmacytoma have also arisen in areas of local trauma (TISP).2-7 Patients with TISP typically have a history of stage III MM without previous extramedullary disease and have been recently treated, or are in remission, after chemotherapy with either vincristine-adriamycin-dexamethasone3,5,6 or melphalan-prednisone-cyclophosphamide,2,4,7 with or without bone marrow transplantation. Patients range in age from 542,4 to 777 years, and duration of remission prior to TISP is up to 7 years.2 The types of MM primaries are IgG or IgA with κ or λ light chains, most commonly IgG κ, and the phenotype of the secondary lesions match the primary in each case.2-7 The types of trauma associated with TISP include indwelling or recently removed central venous catheter,2,3,5,6 sites of subcutaneous heparin injection,6 or injury to a limb.4,7 Treatment of TISP with localized radiation and/or chemotherapy typically leads to regression of these lesions, but despite this, systemic progression of MM most commonly leads to the death of the patient, with a median survival of 5 months.2-7 It has been proposed that in TISP, chemotherapy of the primary MM leads to the selection of therapy-resistant plasma cells expressing the cytokine receptor CXCR4, which responds to inflammatory cytokines released from tissue trauma including stromal cell-derived factor-1,interleukin 6, 3, and 10, and tumor necrosis factor.4,6 The differential diagnosis of TISP includes a foreign body6 secondary neoplasm, persistent injury,4 and cellulitis. Clinicians should consider TISP in patients with a history of MM who have sustained injuries that fail to heal normally. A biopsy with immunologic staining will confirm the diagnosis. Return to Quiz Case. References 1. Wong KFChan JKLi LPYau TKLee AW Primary cutaneous plasmacytoma—report of two cases and review of the literature. Am J Dermatopathol 1994;16 (4) 392- 397PubMedGoogle ScholarCrossref 2. Stellato TAGauderer MWKazura J Tumor metastasis from multiple myeloma and Burkitt's lymphoma in Broviac catheter tracts. Cancer 1985;55 (11) 2715- 2717PubMedGoogle ScholarCrossref 3. Davidson NG Tumour metastasis from multiple myeloma in Hickman catheter tract. Eur J Surg Oncol 1990;16 (2) 170- 171PubMedGoogle Scholar 4. Trullemans FSchots RStorme GCamp BV Late and localized extramedullary relapse of a light chain κ myeloma after syngeneic bone marrow transplantation. Bone Marrow Transplant 2000;25 (1) 115- 117PubMedGoogle ScholarCrossref 5. Kerob DVantelon JMRibrag V et al. Cutaneous localization of multiple myeloma on the tract of a central venous catheter [in French]. Ann Dermatol Venereol 2002;129 (3) 311- 314PubMedGoogle Scholar 6. Rosenblum MDBredeson CNChang CRizzo JD Subcutaneous plasmacytomas with tropism to sites of previous trauma in a multiple myeloma patient treated with an autologous bone marrow transplant. Am J Hematol 2003;72 (4) 274- 277PubMedGoogle ScholarCrossref 7. Pereira MABaudrier TCosta AMagalhães JAzevedo F Cutaneous metastatic plasmacytomas with tropism for a previously injured limb. Dermatol Online J 2008;14 (9) 16PubMedGoogle Scholar