BMW24: MAST CELL SARCOMA INVOLVING THE PERITONEAL CAVITY IN A PATIENT WITH
A HISTORY OF GAMMA/DELTA T-CELL LYMPHOBLASTIC LEUKEMIA/LYMPHOMA
Arash Mohtashamian, LoAnn C Peterson and Amy Chadburn
Northwestern University Feinberg School of Medicine, Division of Hematopathology, Department
of Pathology, Chicago, USA
arashmohtashamian@yahoo.com
Clinical history: The patient is a 34 year old man who presented with intractable nausea/vomiting, diarrhea,
ascites and jaundice in October, 2009. The patient was previously diagnosed with a gamma/delta T-cell
lymphoblastic leukemia/lymphoma (April, 2008) with recurrence refractory to chemotherapy. As a result, he
underwent a matched sibling donor allogenic hematopoietic stem cell transplant with etoposide/XRT
conditioning in December, 2008. His clinical course after transplant was complicated by presumed fungal
infection of the lung and grade I graft versus host disease (GVHD) involving the liver and gastrointestinal tract.
A bone marrow biopsy after stem cell transplantation was not performed, however, peripheral blood
specimens obtained on several occasions showed no involvement by acute leukemia by morphology or flow
cytometeric immunophenotypic analysis. During the current admission, his symptoms were initially thought to
be due to GVHD, however, he developed a prominent ascites and imaging studies showed small bowel
thickening, with peritoneal nodularity and subcentimeter liver lesions. A paracentesis and later biopsies of
omentum, liver and duodenum showed involvement by an abnormal mast cell infiltrate. A bone marrow biopsy
was not performed due to patient's grave prognosis and he was discharged home on palliative care, soon
after which he expired in early November, 2009.
Hb 10.8 g/dl (Reference range 13.0-17.5 g/dl), WBC 13.3 k/ul (Reference range 3.5-10.5 k/ul), Plt 179 k/ul
(Reference range 140-390 k/ul). Other lab. parameters: MCV 89 fL (Reference range 80-99 fL), RDW 16.8%
(Reference range 11-14%), AST 95 U/L (Reference range 15-37 U/L), ALK Phosphatase 1400 U/L (Reference
range 50-136 U/L), Bilirubin, Total 9.17 mg/dl (Reference range 0.00-1.00 mg/dl), Protein, Total 5.0 g/dl
(Reference range 6.4-8.2 g/dl), Albumin 1.4 g/dl (Reference range 3.4-5.0 g/dl), ALT 174 U/L (Reference
range 30-65 U/L), Serum tryptase: 33.9 ug/L (Reference range 1.9-13.5 ug/L).
Biopsy: Omental biopsy: Formalin fixative. Bone marrow biopsy: B5 fixative.
Microscopy: Omental biopsy (9 October 2009): The omental tissue is infiltrated by sheets of
atypical/abnormal mononuclear cells with large round to oval nuclei and ample eosinophilic cytoplasm.
Scattered mitotic figures are identified, some of which appear atypical. Bone marrow biopsy (right core; 16
April 2008): The bone marrow is hypercellular (~95% cellular) and shows diffuse effacement by lymphoblastic
cells which involve ~95% of the bone marrow. Myeloid and erythroid precursors are markedly decreased.
Megakaryocytes are adequate in number. Bone marrow aspirate smear (16 April 2008): There are sheets of
large mononuclear cells with scant basophilic cytoplasm, finely dispersed chromatin and prominent nucleoli.
Myeloid precursors are decreased and only a few segemented neutrophils are identified. Megakaryocytes are
present and appear unremarkable. Erythroid precursors are decreased but appear unremarkable. Peripheral
blood smear (obtained at the time of the original bone marrow biopsy): The peripheral blood smear shows a
normocytic normochromic anemia with increased polychromasia and occasional tear drop forms. The white
blood cells are increased and predominantly consist of abnormal blasts characterized by large cells with scant
cytoplasm, open chromatin and prominent nucleoli. The abnormal cells contain no Auer rods. Platelets are
slightly decreased with unremarkable morphology.
Immunohistochemistry: Omental biopsy (9 October 2009): AE1/AE3: Negative, Myeloperoxidase: Negative,
CD2: Rare cells are positive, CD3: Negative, CD20: Negative, CD25: Highlights the vast majority of tumor
cells, CD68(PGM-1): Stains macrophages, CD68(KP-1): Highlights the vast majority of tumor cells, Tryptase:
Highlights the vast majority of tumor cells, CD123: Faintly stains some cells., CD117: Highlights the vast
majority of tumor cells, Giemsa: Focally cells with giemsa positive granules are identified. Original bone
marrow biopsy: Tryptase: Highlights scattered cells.
Flow cytometeric immunophenotypic analysis: Ascites fluid: Showed an abnormal population of mast cells
that are CD117+, tryptase+, bright CD25+, CD2+, and bright CD33+. Original bone marrow aspirate: Showed
an abnormal T-cell population with bright CD3, CD2, CD5 and CD7 staining. The abnormal T-cells showed
dim TdT staining, dim to partial CD1a staining but no CD34 staining. These cells were gamma/delta positive
but CD4-/CD8-.
Cytogenetics: Bone marrow (24 April 2008): No clonal abnormality detected, normal male karyotype- 46,
XY[20]. Peritoneal fluid (19 October 2009): Complex clonal numerical and structural abnormalities showing the
following abnormalities: 77-88,XXY,-Y, -2,add(2)(p11.2),add(3)(p13),add(3)(q12)x2,-4, -4,add(4)(q12),
add(5)(q11.2)x2,add(6)(p21),-8,-8,-8,-9,-9,add(9)(p13)x2, add(10)(p15),-11,-11, add(12)(p13),-
13,del(13)(q12q14),der(14)t(11;14)(q13;q24)x2, dic(15;?)(p11.2;?),-16, add(16)(p13.3)x2,add(16)(q22),-17,17,del(17)(p11.2)x2,-21, -22,+9-14mar[cp20]
Molecular analysis: T-cell receptor rearrangement by PCR (21 April 2008) performed on the peripheral
blood: Positive for T-cell receptor gene rearrangement; a 187 bp band using the TCRA master mix, and no
bands using the TCRB master mix. KIT FOR MASTOCYTOSIS AND FIP1L1 PDGFRA: Negative for C-Kit and
FIPL1 PDGFRA mutations.
Proposed diagnosis
Omentum and liver (9 October 2009): Mast cell sarcoma.
Bone marrow biopsy (16 April 2008): T-cell lymphoblastic leukemia/lymphoma; no evidence of
involvement by a mast cell neoplasm.
Interesting feature(s) of the submitted case
1. Mast cell sarcoma is an extremely rare form of mastocytosis with only rare well documented cases in the
literature.
2. This case is also interesting since it was diagnosed in a patient with a prior history of gamma/delta T-cell
lymphoblastic leukemia with GVHD after an allogenic stem cell transplant.