| Session: Extramedullary manifestation of neoplastic myeloid disorder |
| Case number: 172 |
Submitter(s): Sandeep K. Gurbuxani, Elizabeth M. Hyjek, Jerome I. Dickstein, Yanming Zhang, John Anastasi.
Clinical history
The patient is a 70 yr male who presented to an outside hospital in 4/05 with a right flank skin lesion that was diagnosed as a large B cell lymphoma, high grade. The reported phenotype was: CD45+, BCL2+ and partial CD20+ and CD10+. The process appeared localized, and the bone marrow was negative, but did show a low grade plasma cell dyscrasia. The patient was treated with radiation and CHOP-R chemo x6, and achieved clinical remission.
Over one year later, in 9/06, the patient developed circulating malignant cells in his blood, and was referred to the U.of Chicago. A bone marrow study showed blasts in blood and marrow. The phenotype was confusing with CD13, CD33, CD4, CD7, and partial expression of the B markers CD20, cyCD79A but with lack of CD19 and CD56. The case was considered an acute leukemia of ambiguous lineage, possibly therapy-related, and the patient was treated on an AML protocol.
The patient achieved a partial remission, but within 4 months relapsed with blasts in the blood and numerous skin lesions throughout his body. At relapse lab values were: WBC:15.4K/ul, HgB:10.5g/dl, Plat:22.K/uL.
Details of gross/microscopic pathology:
Skin Lesion at diagnosis and relapse: normal epithelium, slight grenz zone, diffuse dermal infiltrate of large immunoblast-like cells (fig.1,2)
Leukemic Process initally and at relapse: (fig.8,9) Primitive appearing large blasts in blood and marrow with oval nuclei with fine, blastic chromatin, single/multiple large nucleoli, and abundant deep blue cytoplasm without granulation. Normal appearing residual hematopoiesis.
Immunophenotype (flow cytometry/immunohistochemistry):
Skin Lesion: final phenotype of initial and relapsed specimens: diffuse positivity for CD45, CD4, CD7, CD43 (fig.3), BCL2,CD123 (fig.4); focal positivity for CD20 (fig5), CD10, CD79A(fig.6); TdT (fig.7), negative for CD56.
Leukemic Process: Cytochem: MyPx-, ANA-,NCA-; Flow: CD45+, DR+, CD4+, CD7+,CD13+, CD33+, partial positivity for CD20, CD79A, CD10. The cells were negative for CD34, CD1a, CD2, cy/surfaceCD3, CD8, CD5, CD56, CD19, CD24, sIg, CD14, CD15, CD11b, CD117, Glycophorin A, and CD41. At relapse the blasts became CD56+.(fig.10)
Cytogenetics:
t(6;8)(p21;q24.1),del(13)(q12q14).
Molecular analysis:
Both the peripheral blood (at relapse) and initial skin specimen showed clonal IgH rearrengements of the incomplete (DJ-H) type. TCR[gamma] gene rearrangement showed no clonality.
Interesting feature(s) of submitted case:
Plasmacytoid dendritic cell tumor initially misdiagnosed as large B cell lymphoma, then as an acute leukemia of ambiguous lineage due to initial lack of CD56 and partial expresson of B cell markers and TdT.
The case also points to the likely multipotentiality of the precursor cell involved which seems capable of giving rise to plasmacytoid/myeloid dendritic/B-lineage cells.
Proposed diagnosis:
Plasmacytoid Dendritic Cell Tumor.
Panel diagnosis:
agree with proposed diagnosis
Comments:
Stains performed by the panel: CD123+, NPM- (+in nuclei); CD56 positivity dependent on the epitope tested.
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