Granulocytic sarcoma, as known as chloroma, myeloblastoma or extramedullary myeloid cell tumor, is a localized extramedullary tumor composed of one or more of the myeloid lineages [1,2], It usually presents as a nodular mass in the course of acute myeloid leukemia or associated with various myeloproliferative diseases, occurring in any age and affecting all parts of the body. Rarely, the tumor can develop in a patient after complete remission from the acute myeloid leukemia [1] and it suggests the recurrence of leukemia and the poor prognosis. Here we present an unusual case, the patient developed granulocytic sarcoma seven times after longstanding complete remission from AML-M1 without BM and peripheral blood involvement. Curiously, the patient remained normal of blood count and BM for 34 years until he died.
Clinical history
In May 1988, a 40-years-old man found two masses in the left popliteal fossa and right maxillary sinus. Mass at popliteal fossa was partially resected and postoperative pathological diagnosis was synovial sarcoma. The patient received chemotherapy and radiotherapy and then the mass in the right maxillary sinus was disappeared and the clinical symptom was completely relieved.
In October 1992, two masses were found in left epididymis near the sperm duct and spermatic vein, respectively. The surgically excised tissues were sent to the pathology department. We reviewed the previous hematoxylin-eosin (HE) section and inquired about the patient’s detailed medical history. Unexpectedly, we learned the history that the patient had got acute myelogenous leukemia(AML-M1) in 1982. Therefore, chloro-acetate esterase (CAE) histochemical staining was performed and supported the diagnosis of granulocytic sarcoma. Combining morphological features with a a detailed history and CAE staining results, we rendered a diagnosis of granulocytic sarcoma. The previous diagnosis of popliteal fossa biopsy was also revised as granulocytic sarcoma. However, hemogram and myelogram were normal all the time. The patient received chemotherapy and discharged.
Another subcutaneous mass was found in the right forearm in November, 1997. The mass was removed by surgery, and pathological diagnosis from outside the hospital was lipofibroma with chronic inflammation. Another local mass was noted shortly after the operation. The tumor grew to the fist-size after 6 months, so the patient was admitted to our hospital again, and the clinical suspected that it was granulocytic sarcoma, not fibrosarcoma. The patient was given surgical resection in July 1998. The pathological diagnosis was granulocytic sarcoma. BM aspiration showed no evidence of systemic relapse. After treatment, the patient achieved complete remission and discharged from our hospital.
From August 1998 to April 2003, the patient had occurred extramedullary relapse four times. The details were shown in table 1 and H&E stain shown in Fig 1. The blood count and BM were always normal. After 2003, he did not develop granulocytic sarcoma or leukemia again until his death in October 2016. The timeline of his illness is clearly shown in Fig 2.
Pathologic finding
All of the dissected tissues were given retrospective HE staining and immunohistochemical staining. The microscopic histologic findings were roughly the same: tumor cells were proliferated diffusely in the popliteal fossa, subcutaneous adipose tissue of the forearm, the area between skeletal muscles, the area below nasal mucosa epithelium and area between seminiferous tubules. While focal aggregation and infiltration of the tumor cells were found in epididymal mesenchyme. The tumor cells also invaded into the surrounding soft tissue. Some tumor cells were arranged in “Indian file”. The tumor cells were of medium size and relatively consistent shape. The cytoplasm was little and lightly dyed, while the nuclei were in round or ovoid. Nuclear chromatin was fine and distributed uniformly. 1 or 2 small basophilic nucleoli can be seen. Mitosis was common, with 1~2/HPF. Immature eosinophil was not seen. It was blast type granulocytic sarcoma based on the histological classification. A panel of antibody including MPO, CD34, CD117, CD43, CD15, CD68（PG-M1）, CD68（KP1）, CD56, LCA, CD99, CD3, CD20, and Ki-67 were used to make immunohistochemical staining by streptavidin-perosidase method. The results of immunohistochemistry stains showed in Table Ⅱ. Immunohistochemical results of our case are all the same, suggesting that they were all derived from the recurrence of the same tumor.