[Concomitant myeloid sarcoma and plasma cell myeloma--case report of a hitherto undescribed association of two neoplasms].

A 65-year-old male patient initially presented with a penile tumour, identified as myeloid sarcoma. Subsequent bone marrow investigation revealed the presence of a synchronous plasma cell myeloma, without any evidence of a bone marrow-based myeloproliferative disorder. Although the course of both neoplasms was progressive, with increasing bone marrow involvement by the plasma cell myeloma and cutaneous dissemination of the myeloid sarcoma, both neoplasms remained confined to their original tissue compartments. Different biology of both tumours, including markedly divergent response to therapies, contributed to a significant clinical dilemma and finally to the patient demise 16 months after the presentation. While the association of plasma cell myeloma and various myeloid leukaemias is well documented, this is a first report of simultaneous occurrence of a myeloma and a myeloid sarcoma.