Soft tissues granulocytic sarcoma Clinical characteristics and imaging features J.A. Jimenez-Lasanta, L. Castro, C. Roque, R. Rodriguez, S. Mourelo, A. Olazabal HUGTIP–Badalona. SPAIN

Purpose  To present the clinical and imaging characteristics of this tumor when it involves muscles or muscle groups or, in general, the soft tissues.  To describe sonographic B-mode, color Doppler and contrast ultrasound findings, outlining the value of puncture-biopsy for diagnosis.  To compare US features with those found by other imaging techniques.  To correlate this appearance with the histological findings and to establish a differential diagnosis.

Subject review 1.- What is this disease?  Myeloid sarcomas, according to a recent classification from the Hematopoietic and Lymphoid Neoplasms WHO, are extramedullary granulocytic tumors that were known as granulocytic sarcomas, extramedullary leukemic tumors or chloromas.  They are tumors composed by myeloid cells at different maturation stages that occur in extramedullary location.  They occur in 2-3% of patients with acute myeloid leukemia (AML) and 4-5% of those with chronic myeloid leukemia (CML).  They may appear isolated and precede by months an AML or a blastic transformation of CML.

Subject review 2.- Current diagnosis and therapy  Any involved anatomical location can be found, although the most common sites are skin, lymph nodes, underlain by soft tissue on bone, bone-periosteum and viscera.  The diagnosis is based on the presence of neutrophils and myelocytes positive staining for myeloperoxidase (MPO) and/or naphthol AS-D-cloroacetatoesterase.  Single lesions are most common and, in general, they are sensitive to irradiation.  In principle, the recommended treatment is the same that the used in systemic AML, but it's useful to be aware that up to 25% of patients do not necessarily will develop AML.

Material and methods  A retrospective study was made of patients seen during more than 15 years in our tertiary hospital.  A total of 12 patients with clinical suspicion of myeloid sarcoma was found  19 patients had soft tissue involvement, with an age range between 7 and 65 years.  All patients were firstly examined by US using high frequency probes (8-15 Mhz).  The US machines used in these patients were Sequoia 512 and Antares Acuson-Siemens.

Chloroma of the SCM muscle  A 61-year-old patient admitted with toxic syndrome and left laterocervical lump.  US was performed to image this mass.  Subsequently, this patient developed AML. ECM chloroma. Longitudinal B-Mode US of the left laterocervical region shows a well-defined hypoechoic mass

Cross section B-mode which shows how this well-defined mass infiltrates the fibrillar component Color Doppler demonstrates significant internal and peripheral vascular flow.

Histological exam discloses a positive myeloperoxidase staining, which is typical of granulocytic sarcomas.

Myeloid sarcoma involving the quadriceps  A 67-year-old patient presented with acute myeloid leukemia  He received induction and consolidation chemotherapy with total body irradiation followed by bone marrow transplantation.  Several months after clinical stabilization, the patient presented with progressive myalgia, predominantly in the left thigh.  Patient had slight fever for 10 days, with discrete inflammation involving the left quadriceps muscle group.

B-mode US, cross-section of rectus femoris muscle, with a hypoechoic infiltration of the muscle fibers. B-mode US, longitudinal section, with involvement of the entire muscle without subcutaneous implication.

Color Doppler

Panoramic views

 A septic complication was suspected in that location, although no associated collections were seen by US.  Polymyositis was also considered as a differential diagnosis.  Biopsy of the affected area of the rectus femoris was performed with a 14G needle, guided by ultrasound, with no evidence of complications. Myeloid sarcoma of the quadriceps Differential Diagnosis

Muscle fibers present degenerative changes and show infiltration by medium sized cells with an immature chromatin and scant cytoplasm, typical of myeloid sarcoma. Myeloid sarcoma of the quadriceps Histology

Olecranon bursa. Another location of the disease is shown in the same patient who had multicentric involvement. Myeloid sarcoma of the elbow

Longitudinal muscle level Myositis-like pattern of the disease in a patient with CML, who suffered an outbreak of blasts a few months before. Diffuse myeloid sarcoma of SCM Panoramic view in longitudinal section.

Longitudinal color Doppler US discloses marginal tissue hypervascularity. Diffuse myeloid sarcoma of SCM Disease infiltration respects the surrounding tissues.

Granulocytic sarcoma involving the synovial sheath Longitudinal B-mode in a patient with AML, shows a mass that mimics a synovial sheath tumor Cross section

Granulocytic sarcoma involving axillar region Patient with history of AML in remission. Cross-sectional B- mode US discloses a hypoechoic mass. On Color Doppler the hypoechoic mass discloses a significant hypervasculature, mimicking atypical or malignant lymphadenopathy. Compare with a nonspecific lymph node (arrow) shown on the left.

Suggested Readings 1- Jan Fritz, Wichard Vogel et al. Generalized intramuscular granulocytic sarcoma mimicking polymiositis. Skeletal Radiol 2007;36: G.C.Ooi, C.S. Chim, et al. Radiological manifestations of granulocytic sarcoma in adult leukemia. AJR 2001:176: Rizzo M, Magro G, et al. Granulocytic sarcoma in HIV patient: a report. Forensic Sci Int 2004;146 Suppl:S Scheipl S, Leithner A, et al. Myeloid sarcoma presenting in muscle-tissue of the lower limb: unusual origen of a compartment-syndrome. Am J Clin Oncol 2007;30(6):658-9.