multiple myeloma is a monoclonal malignant neoplasm of plasma cell origin which occurs in the bone marrow and may result in extensive destruction of skeletal structures . it most commonly affects the skull , vertebrae , and pelvis , with pain , fatigue , swelling , and anemia being some of the most common clinical presentations . an 83-year - old african american female presented to the emergency department with mild pain and swelling over the posterior left mandibular alveolar ridge [ figure 1 ] . the lesion was approximately 2 cm  2 cm  1.5 cm in the area of the missing first molar . on palpation , it was firm with no fluctuance . radiographically , an ill - defined radiolucency of the alveolar bone was identified [ figure 2 ] . initial clinical presentation of the patient with gingival swelling between teeth 18 and 20 radiograph showing an ill - defined radiolucent area in the bone between teeth 18 and 20 an incisional biopsy revealed a malignant neoplasm of hematopoietic origin with sheets of malignant plasma cells ranging from mature to immature forms as well as pleomorphic - cells and occasional binucleated cells [ figure 3 ] . the neoplastic plasma cells were strongly positive with kappa light chain antibody and with cd138 [ figure 4 ] , both supporting the histological diagnosis of plasmacytoma . ( a ) low magnification shows stratified squamous mucosa on right upper end with cellular infiltrate in left lower portion of the image ; ( b ) magnification of h and e histology shows sheets of plasma cells , most are large and atypical with large nuclei and prominent nucleoli immunohistochemistry stain for cd138 antibody . note uniform positive staining with cd138 , a marker for plasma cells a bone marrow aspirate biopsy was performed on the left posterior iliac crest where sheets of neoplastic plasma cells were identified . a random urine collection showed elevated bence - jones protein ( 0.09 g ) and a subsequent 24 h urine collection demonstrated a level of 0.13 g ( normal 0.0500.080 ) . the disease is usually found in the sixth and seventh decades of life with a median age of 62 , 66 , 71 . it is a multicentric and generalized bone marrow disease that affects multiple bones and can include the jaws . in a review of 193 patients with diagnosed multiple myeloma , epstein et al . reported that out of 783 multiple myeloma patients , 14.1% had oral manifestations in the form of jaw pain , severe periodontitis , tooth mobility , bone destruction , pathologic fracture , paresthesia , and soft tissue swelling . usually , if the jaws are involved , it is an indication of an advanced stage of the disease . in the case we report , no other lesions were identified on the osseous skeletal survey performed the same month as the biopsy . this patient had a systemic manifestation of multiple myeloma despite the jaw being the only bone affected ; she had mild anemia , elevated serum calcium , and bence - jones protein in her urine . she also had sheets of neoplastic plasma cells in her bone marrow biopsy performed on the left posterior iliac crest . the neoplastic plasma cells were positive with cd138 antibody confirming the presence of the disease in an area away from the jaw . we present a case of multiple myeloma first manifesting in the mouth as a mildly painful gingival swelling with underlying irregular bone destruction . we recommended that all patients receive a routine oral examination by their dentist and primary care physician to insure early recognition of malignant neoplasms of the mouth .