SimantAnkit,Yi Sun*,Tong-Xiang Zeng

Department of Dermatology and Venereology,Jingzhou Central Hospital,Yangtze University,Jingzhou,Hubei 434100,China.

Introduction

Myeloid sarcoma is a rare malignancy,a tumor mass of myeloblast or immature myeloid cells occurring as an extramedullary tumor often associated with or following acute myeloid leukemia or other myeloid neoplasms but rarely following myelofibrosis.It is difficult to make a correct diagnosis only based on clinical and histopathological findings in such cases due to its rareness.The treatment is based on the type of acute myeloid leukemia.In the present study,a rare case of cutaneous myeloid sarcoma associated with acute myeloid leukemia is reported,which may help to enhance the understanding of this disease.

Case report

In June 2016,a 60-year-old man presented with a 2-month history of red nodules and no other complaints at the Jingzhou Central Hospital.Physical examination showed multiple red nodules of 10 to 30 mm in diameter on his arms,legs,and trunk(Figure 1A).A complete blood count revealed a white blood cell count of 10.96×109/L with 8.5%blast cells,1.0%myeloid cells,3.5%stab cells,27.0%segmented neutrophils,56.0%lymphocytes,36.0%monocytes,0.5%eosinophils,and 0.5%basophils.The platelet count was 37×109/L,red blood cell count was 3.95×1012/L,and hemoglobin level was 146 g/L.The results of other routine investigations such as biochemical tests and urinalysis were normal.Serologic test results for syphilis,human immunodeficiency virus,and hepatitis B and C were negative.A biopsy was taken from a nodule on his abdomen.We found sheets of cells with abundant eosinophilic cytoplasm;enlarged,frequently reniform nuclei;and numerous mitotic figures by microscopic(Figure 1B and 1C).Immunohistochemical studies were positive for CD43 CD45,CD4,CD68,myeloperoxidase,CD56,and lysozyme and negative for CD3,CD117,CD8(Figure 2A-2F),CD20,EBER,TIA1,CD123,and CD79a.Peroxidase staining was negative,confirming the diagnosis of myeloid sarcoma.Peripheral blood blood cell count showed that 12% of cells were abnormal.Bone marrow cytology indicated significantly active hyperplasia.The numbers of granulocytes and erythrocytes were relatively rare,and the lymphocytes accounted for 1.5%.About 87%of bone marrow cells were abnormal,with basophilic cytoplasm containing vacuoles and purple granules and a round nucleus containing coarse chromatin.No megakaryocytes and few platelets were present(Figure 3).At our request,a hematologist examined the patient,and made a diagnosis of acute myeloid leukemia.

Based on this diagnosis,the patient was administered induction chemotherapy with intravenous enocitabine and aclarubicin hydrochloride.However,he refused further therapy and was lost to follow-up.

Discussion

Figure 1 Clinical presentation of the patient and the pathology of the biopsy sample.A:Multiple red nodules on the trunk.B and C:Sheets of cells with abundant eosinophilic cytoplasm;enlarged,frequently reniform nuclei;and numerous mitotic figures.B:H&E,×10.C:H&E,×40.Figure 2 Immunohistochemistry results of lesions.A:CD43+.B:CD68+.C:MPO+.D:CD56+.E:CD117-.F:CD8-.

Myeloid sarcoma is a rare extramedullary tumor and complicated disease that can develop in the absence of other systemic diseases.It is characterized by high mortality.The 2008 version of the World Health Organization Classification of Tumors of Haematopoietic and Lymphoid Tissues and its revised 2016 version defined myeloid sarcoma as“a tumor mass consisting of myeloid blasts with or without maturation occurring at an anatomic site other than the bone marrow”[1-2].The disease can be classified into four types according to the tumor cell type:granulocytic sarcoma,primitive monocytic sarcoma,myeloid sarcoma of hematopoietic cells,and primary myeloid sarcoma without presentation of other hematological diseases.Myeloid sarcoma can also occur as blastic transformation with myelodysplastic syndrome,myelo-proliferative neoplasm,or a combination of the two[3].It is more common in women aged 45 to 56 years.Myeloid sarcoma affects the lymph nodes,skin,bones,abdominal organs,testes,and lacrimal glands.Skin lesions generally occur on the trunk,scalp,and face,but in the present case,skin lesions were found on the arms,legs,and trunk.The proportion of patients with type M2 acute myeloid leukemia that progresses to myeloid sarcoma is 10%,and those with acute myelocytic leukemia accompanied by myeloid sarcoma is 2%to 8%[4].Myeloid sarcoma may also develop in patients who previously undergo chemotherapy for treatment of cancer.In a minority of patients,myeloid sarcoma can be an initial disease[3].In the present case,comprehensive pathological evaluation confirmed the diagnosis of myeloid sarcoma with aberrant expression of CD56 and the translocation t(8;21)[4],which occurs in part patients with acute myeloid leukemia.Aberrant antigen expression by cutaneous myeloid sarcomas can cause diagnostic confusion with other cutaneous neoplasms[5],such as diffuse large cell lymphoma and Ewing’s sarcoma.Patients presenting with features of myeloid sarcoma should receive combined treatments as soon as possible.The prognosis of this disease remains dismal due to its particular pathogenesis and genomic landscape,which are not well understood even in this modern era.Therefore,every case gives us an opportunity to improve our knowledge and treatment of this rare disease.

Figure 3 Bone marrow cytology showing many abnormal cells(87%).The cytoplasm was basophilic with vacuoles and purple granules,and the nucleus was round with coarse chromatin(Wrights stain,×180).

In summary,cutaneous myeloid sarcoma with acute myeloid leukemia are particularly a rare entity.Only few cases are reported so far.Indeed,the diagnosis may be challenging but with the help of patient clinical history,biopsy and histopathology,myeloid sarcoma can be differentiated from another carcinoma.We reporta unique case,which improve our knowledge and help us to understand the complexity of the disease.

Acknowledgments

This work was supported by the National Natural Science Foundation of China(No.81401677)and the Hubei Province Health and Family Planning Scientific Research Project(No.WJ2015MB281).