| Session: Extramedullary manifestation of neoplastic myeloid disorder |
| Case number: 207 |
Submitter(s): Claudio A. Mosse.
Clinical history
The patient is a 79 year old white male with no significant past medical or surgical history. He presents with abdominal pain of two weeks duration. CBC is not available.
Colonoscopy identified a non-ulcerating mass in the transverse colon. Endoscopic biopsies were non-diagnostic at an outside hospital. On CT, this mass was "several" centimeters in diameter and appeared to encroach the transverse colon invading into the mucosa rather than arising within it. Exploratory laparotomy was performed and identified numerous masses in the mesentery and adjacent to the transverse colon.
Details of gross/microscopic pathology:
Gross Description:
Four fragments of gray/tan tissue each measuring approximately 2cm in diameter. Also submitted was a tan/gray "mass in gastrocolon ligament" that measured 4.2 x 4.0 x 2.5 cm weighing 10 gm. A portion of this specimen is sent for flow cytometry.
Microscopic Pathology:
Multiple pieces of tissue show diffuse invasion of fat and soft tissue by medium sized cells with moderate pale cytoplasm and pleomorphic nuclei with moderately dispersed chromatin.[figure1]In areas, the cells appear to be streaming through dense fibrosis.[figure2]The mass in the "gastrocolon ligament" is a lymph node that shows an interfollicular pattern of infiltration by neoplastic cells.[figure3]The cells have moderate amounts of pale cytoplasm, pleomorphic nuclei with moderately dispersed chromatin and indistinct nucleoli.[figure4]Although many follicles are intact, others are destroyed by the neoplastic cells.[figure5]The neoplastic cells obliterate the sinuses and capsule with extracapsular extension into perinodal fat.
Touch Preparations
Cells are found scattered in clusters and individually. The cells have scant pale cytoplasm with round to reniform nuclei, dispersed chromatin and small to indistinct nucleoli.[figure6]Cytospin Preparation of Sample Sent for Flow Cytometry:
The specimen is comprised of large cells with moderate amounts of cytoplasm, reniform to round nuclei and dispersed chromatin.[figure7]
Immunophenotype (flow cytometry/immunohistochemistry):
The pertinent flow cytometric plots are shown.[figure8]This population expresses bright CD45, moderate CD33 without CD19. The neoplastic cells express bright HLA-DR, bright CD7, moderate CD117 and are negative for CD34. There is expression of myeloid markers CD13, CD64 and dim levels of CD14. There is no expression of CD1a, CD8, CD5 or CD2. There is no expression of either cytoplasmic MPO, cytoCD79a or cytoCD3.
Immunohistochemistry reveals the atypical cells to be strongly positive for lysozyme and CD43. The neoplastic cells do not express myeloperoxidase or CD3.
Cytogenetics:
N/A.
Molecular analysis:
N/A.
Interesting feature(s) of submitted case:
While extramedullary myeloid tumors are not rare presentations of acute myeloid leukemia, the presentation in this case was unusual with abdominal pain as the presenting symptom and suspected adenocarcinoma of the colon as the pre-operative diagnosis.
Proposed diagnosis:
Extramedullary Myeloid Tumor.
Panel diagnosis:
agree with proposed diagnosis
Comments:
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