2008, Volume 24, Number 3, Page(s) 183-185
Mediastinal granulocytic sarcoma
Bahar AKKAYA1, Esin ÖZEL1, İhsan KARADOĞAN2, Hüseyin BEKÖZ2, Gülten KARPUZOĞLU1
1 Akdeniz University School of Medicine, Pathology Department, ANTALYA
2 Akdeniz University School of Medicine, Hematology Department, ANTALYA
Keywords: Granulocytic sarcoma, chloroma, myeloid sarcoma
Granulocytic sarcoma is an unusual variant of myeloid
malignancy in which there is an extramedullary tumor
mass composed of myeloblasts or myeloblasts and more
mature neutrophils. It rarely occurs in mediastinum
and clinically may resemble a mediastinal lymphoma.
We report a patient who was initially diagnosed as malignant
lymphoma based on the previous biopsy specimen.
The diagnosis of granulocytic sarcoma is not difficult
with careful histopathologic evaluation and immunohistochemical
Granulocytic sarcoma (GS), also known as
chloroma, myeloid sarcoma and leucosarcoma,
is a rare tumor composed of immature myeloid
cells. The common sites of involvement include
the small intestine, skin, bone and lymph nodes.
GS has been reported in liver, spinal cord, gynecologic
tract, cerebellum, small bowel and urinary
. Most cases of GS occur during
the progression of leukemia. They are usually
associated with acute myeloid leukemia and
less commonly with blastic transformation of
chronic myeloid leukemia and myelodysplastic
syndromes. Rarely, these tumors may be observed
before the diagnosis of any hematological
malignancy. In such cases, granulocytic sarcomas
may be misdiagnosed as lymphoma.
We hereby report a case of GS presenting
as a mediastinal mass in a 29-year-old woman
without a history of leukemia. The case initially
diagnosed as malignant lymphoma on the previous
A 29-year-old woman was admitted to local
hospital because of respiratory distress. Radiologic
examination revealed a 9,5 cm-sized
mediastinal mass. She underwent surgical resection
of mediastinal mass. The tumor was diagnosed
as diffuse non-Hodgkin, large cell
lymphoma. At that time, there was no clinical
and laboratory evidence of acute myeloid leukemia
or chronic myeloproliferative disease. The
patient was treated with CHOP (cyclophosphamide,
hydroxydoxorubicin, Oncovin, prednison)
and then with palliative chemotherapy.
Three months after her initial presentation, she
was admitted to Hematology Department of Akdeniz University. The paraffin-embedded blocs
were referred to Pathology Department of Akdeniz
University for a second opinion. Histologically,
there were sheets of immature cells and
the cells had round and oval nuclei with scantly
cytoplasm. It had a delicate nuclear chromatin
pattern with thin, regular nuclear membrane,
and one or more small basophilic nucleoli (Figure 1
). These cells stained positively with leukocyte
common antigen (LCA), CD68, CD43.
But antibodies for specific T cells (CD3, CD5,
CD2) and B cells (CD20, CD79a) antigens did
not stain. Because of CD68 and CD43 positivity,
the sections were further stained with
CD30, ALK-1 and myeloperoxidase to exclude
lymphoma. Myeloperoxidase was positive
). AKL-1 and CD30 were negative. No
cytoplasmic granules could be recognized in a
thin Giemsa section. The tumor was diagnosed
as granulocytic sarcoma. The patient had been
misdiagnosed as a lymphoma. A bone marrow
aspirate and trephine biopsy, taken a month later,
showed normal cellularity and no lymphomatous
Click Here to Zoom
|Figure 1: Diffuse and infiltrative population of small round tumor cells show scant granular eosinophilic cytoplasm. (HE x200).
The bone marrow aspiration showed
hypercellularity with diffuse infiltrating blasts.
Treatment was started with induction chemotherapy
consisting of daunorubicin and cytosinarabinosid.
The bone marrow aspirate one month
later showed no infiltration. Eight weeks after
chemotherapy, she was readmitted with cardiac
failure and died of cardiopulmonary arrest.
Granulocytic sarcoma is an unusual variant
of myeloid malignancy in which there is an
extramedullary tumor mass composed of myeloblasts
or myeloblasts and more mature neutrophils.
GS may occur as an isolated finding or
may be associated with acute myeloid leukemia,
chronic myeloid leukemia, chronic idiopathic
myelofibrosis, hypereosinophilic syndrome, and
polycythemia vera 7
. GS is reported in 0.7-9.0
percent of patients with acute or chronic myelogenous
. The mediastinal mass is an
unusual site of presentation and clinically resemble
a mediastinal lymphoma 9,10
. The diagnosis
of GS is not difficult when the tumor is
grossly green in color, which is due to the presence
of peroxidase in leukemic cells or shows
relatively well-differentiated granulocytes in touch
prints. However, granulocytic sarcomas occurring
as isolated lesions in the absence of some
type of leukemia may be misdiagnosed, as a
malignant lymphoma-large cell type or poorly
differentiated tumors. The higher rate of misdiagnosis
is probably a reflection of the rarity of
this lesions and low index of suspicion. Histopathologic
classification has generally resulted
in three levels of differentiation: blastic, immature, and differentiated. The blastic type is composed
primarily of myeloblasts. The myeloblasts
have a slight to moderate rim of basophilic
cytoplasm, fine nuclear chromatin and two to
four nucleoli. Eosinophilic myelocytes are not
usually found. The immature type with an intermediate
degree of differentiation contains principally
myeloblasts and promyelocytes. The differentiated
type primarily consists of promyelocytes
and cells in their later stages of maturation.
The diagnosis of GS in nonleukemic patients
is extremely difficult without using immunohistochemical
staining. The immunophenotype
is identical to that of a myeloid leukemia being
negative for B and T cell markers but positive
for myeloperoxidase and/or histiocytic markers
such as lysozyme or CD68. Similarly, immunoreactivity
for CD13, CD15, CD33 is expected
in GS but not lymphoma. Other markers
which may be positive include CD31, CD34 and
CD43 and these can be misleading as they are
not lineage specific. For example, CD43 positivity
may suggest a T-cell lymphoma but higher
index of suspicion for a T-cell lymphoma lacking
all other T-cell markers should be maintained.
The use of antibodies against CD34, which
is expressed in acute leukemias, may provide a
useful addition to a panel of antibodies in these
cases, facilitating identification of cells of myeloid
origin excluding lymphoma 11
Due to poor fixation and preparation, histopathologic
diagnosis is difficult without immunohistochemical
staining, nevertheless the
correct diagnosis is made possible by a careful
examination of cytological details. Imprint preparations
of tumor masses may be particularly
useful in identifying the myeloid nature of the
cells. Auer rods may be found and the myeloblasts
may show intense staining with myeloperoxidase
cytochemical reaction. However, eosinophilic
myelocytes are present in 50% of the
cases. Electron microscopic finding of electrondense
granules characteristic of granulocytic
cells is considered pathognomonic of GS.
Histopathologists should be aware of the
fact that granulocytic sarcoma may occur in unusual
extramedullary sites without evidence of
bone marrow involvement. If inappropriate treatment
is to be avoided, a diagnosis of granulocytic
sarcoma should be considered when hemopoietic
tumor cells do not stain with conventional
antibodies against B-and T-lymphoid cells. Both
histochemical and immunohistochemical staining
should be performed in such cases to determine
whether the cells are of myeloid lineage. A
diagnosis of granulocytic sarcoma is not ruled
out when bone marrow biopsy specimens show
no evidence of leukemic infiltration.
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