PMC3970259_01
Computer tomography of the abdomen showing (a) an abnormal soft tissue density involving the sigmoid colon; (b) an enlarged lymph node right to the sigmoid colon; (c) multiple enlarged lymph nodes just below the bifurcation of the abdominal aorta into the common iliac arteries.
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fig1
The visualized portions of the urinary bladder were within normal limits and the kidneys bilaterally demonstrated no hydronephrosis (Figure 1).
Original biopsy diagnostic of an epithelioid malignancy with variable differentiation patterns including solid areas with squamoid features and glandular areas. Diagnosis was of adenocarcinoma with squamous differentiation with qualification to exclude a carcinoma of endometrial origin.
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However, the typical dirty necrosis seen in conventional colonic adenocarcinomas was absent (Figure 2).
PET-CT showing a hypermetabolic rectosigmoid mass with multiple hypermetabolic enlarged lymph nodes.
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fig3
Multiple enlarged lymph nodes just below the bifurcation of the abdominal aorta into common iliac arteries, with a maximum SUV of 9.9, were also seen (Figure 3).
(a) H&E (2x) lower-power microscopic view of the resection specimen with an epithelioid malignancy involving the large intestine; (b) H&E (4x bone and cartilage) low-power view showing both malignant epithelial and mesenchymal elements. The epithelioid component consists of malignant glandular elements with squamous differentiation. The heterologous component (on the right) consists of a malignant osteoid.
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This combined morphology was of a carcinosarcoma (Figures 4 and 5).
(a) (20x) H&E: showing squamous differentiation; (b) (20x) H&E: high power of malignant osteoid.
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This combined morphology was of a carcinosarcoma (Figures 4 and 5).
Immunohistochemistry: (a) (2x) tumor cells are positive for CK7 on the epithelioid components; (b) (2x) tumor cells show no expression for CK20; (c) (2x) tumor cells show strong diffuse expression for estrogen receptor (this immunohistochemical pattern is not consistent with colorectal primaries, but rather with mullerian-derived tumors).
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Immunohistochemistry revealed neoplastic epithelioid cells positive for ER, PAX2, PAX8, CK7, and PR focally and negative for CDX2 and CK20, supporting a mullerian primary (Figure 6).