according to the new world health organization classification , myeloid sarcoma ( ms ) is defined as a tumor mass of immature myeloid cells such as myeloblasts , promyelocytes and myelocytes in an extramedullary site or bone . the high levels of myeloperoxidase enzyme in immature tumor cells are the cause for green discoloration of these tumors . in 1904 , granulocytic sarcoma  in 1966 , because he recognized that the green color is not present in all types of this tumor . the tumor may precede or occur concurrently with acute or chronic myeloid leukemia ( cml ) or with other types of myeloproliferative disorders or myelodysplastic syndromes . myeloid sarcoma is known to be frequently occurring in bone structures such as skull , paranasal sinuses , ribs , sternum , vertebra , pelvis , and soft tissues . however , it may occur in any location such as skin , periosteum , lymph nodes , bronchi , pericardium , peritoneum , orbits , gastrointestinal tract , breast , kidney , bladder , mouth , jaws and reproductive organs . oral involvement of ms is extremely rare intraoral mss usually affect only one site ; in english literature there are only two cases reported involving both maxilla and mandible . this mucosal mass may resemble any carcinoma , pyogenic granuloma , lymphoma , or periodontitis . the exact prevalence of the disease is still unclear due to its low incidence . but according to puranen et al . ms incidence associated with acute myeloid leukemia ( aml ) ranged between 3% and 4.7% . although ms occurs at any age , the most reported cases were diagnosed before the age of 15 years and between the ages of 20 and 44 years . apart from histological diagnosis of ms which is not the only criteria , immunoreactivity with anti - myeloperoxidase is still thought to be the most useful marker . in flow cytometry , it is usually required for detecting myeloid linkage . here we report a case of ms that manifested in gingival mucosa primarily and later spread to multiple organs in 12 months . we aimed to point out the differential diagnosis of this tumor for pathologist due to its high frequency of poorly differentiated histological appearance . a 29-year - old woman appealed to the faculty of dentistry , department of maxillofacial surgery in august 2009 . the patient complained about a painful buccal gingival swelling and bilateral submandibular lymphadenopathy [ figure 1a ] . the patient was initially treated for periodontitis by a dentist . on clinical examination , of gray - brown keratinized , severly painful , sessile lesion at the anterior upper labial gingiva accompanied with submandibular lymphadenopathy in detailed medical history , we found out the patient had weight loss , malaise , night sweats and fever for a while . the patient 's blood test results were as follows : hemoglobin , 10.8 g / dl ; hematocrit , 36.5% ; white blood cell count was 9.2  10/l ( 52.9%monocytes , 23.2% neutrophils , 22.7% lymphocytes , 0.8% eosinophils , 0.4% basophils ) ; platelets , 146  10/l . ( b ) upper buccal gingiva showing gray - brown keratinized swelling an incisional biopsy was performed from the labial vestibular fornix under local anesthesia and sent to department of oral pathology . on gross examination , the excised material showed a central grayish - white non - specific soft tissue material . histologic examination of the biopsy specimen showed monomorphous diffuse infiltrate with a population of immature blast - like cells beneath the intact oral epithelium on panoramic view . the tumor cells were intermediate in size and round to oval in shape with mild to moderate basophilic cytoplasm without granules [ figure 2a ] . some of these cells had pale nuclei containing conspicuous nucleoli , while the others had large angular shaped hyperchromatic nuclei . the tumor cells exhibited loss of cohesion with each other at these areas [ figure 2b ] . also the tumor cells had an increased nuclear - to - cytoplasmic ratio . tumor cells demonstrated pale positive reaction to cd117(c - kit ) [ figure 3a ] and strong positive reaction to myeloperoxidase ( mpo ) [ figure 3b ] monoclonal antibodies ; whereas , negative reactions to s-100 , melan - a , hmb-45 , pan - keratin , kappa , lambda , alpha smooth muscle actin , desmin , cd3 , cd15 , cd20 , cd34 , cd45 and cd68 monoclonal antibodies was observed . ( a ) monomorphous diffuse malignant tumoral infiltrate was seen beneath the oral epithelium ( h & e stain , 40 ) . ( b ) tumor cells exhibited loss of cohesion with each other at these areas . rare mitotic figures were also seen ( arrow ) ( h&e stain , 200 ) ( a ) tumor cells demonstrated pale positive reaction with cd117 ( ihc stain , 200 ) . ( b ) tumor cells strongly positive for myeloperoxidase ( mpo ) ( ihc stain , 400 ) the patient 's submandibular lymph node induration and gingival swelling increased during the time period between biopsy and final histopatological diagnosis was made . after the diagnosis , we consulted the medical oncology department . in pet / ct ( positron emission tomography / computed tomography ) scans , tumor masses were apparent in mandible and on the floor of nasal cavity [ figure 4a ] . the patient received combination of idarubicin and ara - c ( cytosine arabinoside ) chemotherapy regimen at first treatment phase . because of the enlargement of the masses and development of aml , in second chemotherapy session 3 - 5 - 7 ( daunorubicin , etoposide , ara - c ) regimen was performed . bone marrow transplantation was planned after the fourth chemotherapy session but during this hold on period other aggressive tumor masses were found in left lacrimal gland and left breast [ figure 4b ] . unfortunately , the patient died waiting for the appropriate bone marrow transplant and after 15 months of first diagnosis of ms . ( a ) axial pet scan clearly depicts the tumor of the left mandible and floor of the nasal cavity . ms is a solid , localized , extramedullary tumor mass of immature myeloid cells that is often associated with malignant hematopoietic disease such as aml , cmd . presence of ms in the oral tissues is rare , only about less than fifty intraoral ms cases are reported in the literature so far . the most common intraoral locations of ms are the maxillary and mandibular gingiva and bones ; followed by cheek , tongue , parotid , hard palate , soft palate , and lip . xie et al . reported only two cases in which the tumor involved both the maxilla and the mandibular gingiva . thus , in the present case ms involved multiple regions including breast , lacrimal gland , nasal cavity , maxillary gingiva and mandibular soft tissue . in patients who lack a history of pre - existing hematologic disorder , the diagnosis of ms based on just histopathological views differential diagnosis must include soft tissue sarcomas , non - hodgkin 's lymphoma ( diffuse large cell type ) , burkitt lymphoma , large - cell lymphoma , small round cell tumors , ewing 's sarcomas or poorly differentiated epithelial tumors . the case presented in this article did not have any diagnostic statement regarding hematologic disease so this case points out the importance of early and attentive diagnosis of oral manifestations . they reported only four intraoral primary ms cases and concluded that the survival rate of primary ms ( 50.00% ) is higher than ms associated with malignancy ( 22.2% ) . the present case shows an intraoral primary ms associated with aml and the patient deceased about 15 months after diagnosis . recently , it was reported that ms in patients with bone marrow involvement has a higher rate of relapse . xie et al . , reported a case of relapse free patient with only 6-month follow - up . although there is no consensus of follow - up periods in the literature , all authors agreed that a close clinical follow - up is critical . this may cause difficulty in differentiating ms from other malignancies such as large cell lymphoma , poorly differentiated carcinoma or even plasmacytoma . crystalline , rodlike , intracytoplasmic acidophilic bodies ( auer rods ) can establish the diagnosis of both ms and acute myeloid leukemia ; however , they may be present in less than 10% of cases . occasionally the presence of immature eosinophils and maturing neutrophils may indicate the true nature of the lesion . attempts at the histopathological classification have generally resulted in three levels of differentiations : blastic , immature and differentiated cells . myeloid cells contain distinctive primary granules that are not seen in lymphomas or other small blue cell tumors . immunohistochemically , ms myeloblasts usually express myeloid - associated antigens such as cd43 , cd13 , cd33 and cd117 but are not reactive with lymphoid antigens such as cd3 and cd20 . histological appearance directed us to consider small round cell soft tissue tumors for differential diagnosis . a large immunohistochemistry panel was performed and other tumors were eliminated with the exception of tumors originating from hematopoietic tissues . positive staining with mpo and cd117 ( c - kit ) was noted but cd3 and cd20 were negative , which gave important clues to indicate a myeloid neoplasm . distinction of one subtype from the other variants of ms is difficult on the basis of histomorphology alone such as the present case . the co - expression of mpo and cd-117 ( c - kit ) is useful to show granulocytic differentiation of the tumor . ms is a rare malignancy in head and neck region ; hence it is difficult to calculate its incidence accurately . but malignancies diagnosed by dentists have increase in the number of cancers and also more cautious examinations by dentists . it is very well known that various systemic disorders including malignant tumors , even metastatic ones may occur in oral mucosa as the very first sign of disease . gingival masses may be confusing due to high frequency of reactive or neoplastic lesions . a careful oral examination more than usual
myeloid sarcoma is defined as a tumor mass of immature myeloid cells that may be observed in a variety of locations including bone , skin , lymph nodes and soft tissues . however , oral involvement of myeloid sarcoma is extremely rare . 
 these tumors are considered as specific lesions of acute myeloid leukemia . 
 we present a case of a myeloid sarcoma of the upper vestibular gingiva in a 29-year - old woman who has no hematologic disease history . 
 multiple metastases were found in floor of the nasal cavity , left breast , and left lacrimal gland 12 months after primary diagnosis .