| Session: Mast cell disease |
| Case number: 055 |
Submitter(s): Diane A. Hall, Jonathan A. Schumacher, Megan S. Lim, Bertram Schnitzer.
Clinical history
A 67 year-old woman presented with colonic adenocarcinoma. We reviewed selected slides from the colon resection and subsequent bone marrow biopsy slides in consultation. Per report, the patient's serum tryptase level has been persistently elevated above 20 ng/mL. Other medical history, including medication record, is not available.
CBC results: WBC 5900/mm3, Hgb 13.0g/dL, Hct 37.9%, platelet count 362,000/mm3 with 63% neutrophils, 31% lymphocytes, 3% monocytes and 1% eosinophils.
Details of gross/microscopic pathology:
The formalin-fixed right hemicolectomy demonstrated a 5.5 cm mucinous colonic adenocarcinoma arising at the cecum. The adenocarcinoma invaded the muscularis propria (pT2) but did not involve the serosa. Thirty-nine lymph nodes were reported negative for carcinoma (pN0). No information about the presence or absence of metastasis was available (pMX). Furthermore, CD117 and tryptase-positive mast cells densely infiltrated the lamina propria of both adenomatous mucosa adjacent to the carcinoma and distant colonic mucosa uninvolved by dysplasia or carcinoma.
The subcortical bone marrow biopsy (formalin-fixed) revealed a normocellular marrow with trilineage hematopoiesis and increased numbers of CD117 and tryptase-positive mast cells within lymphoid aggregates in the clot section. The mast cells were not spindle-shaped, but were hypogranular in the aspirate.
Immunophenotype (flow cytometry/immunohistochemistry):
Cytogenetics:
Molecular analysis:
Analysis of genomic DNA extracted from the colon paraffin section demonstrated the D816V point mutation in the c-kit gene.
Interesting feature(s) of submitted case:
Systemic mastocytosis has been associated with clonal hematologic non-mast cell lineage diseases. Infrequent observations of systemic mastocytosis with non-hematologic malignancies have been reported. This case represents an unusual presentation of systemic mastocytosis as an incidental finding in a resection specimen for colonic adenocarcinoma.
Proposed diagnosis:
The morphologic features of the colon resection and bone marrow biopsy specimens support a diagnosis of systemic mastocytosis with concurrent colonic adenocarcinoma.
Panel diagnosis:
Intestinal mastocytosis (aggressive systemic mastocytosis)
Comments:
Studies performed by the panel: positive for D816V mutation, CD25+
PowerPoint:
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