Correct!
3. Splenic tissue (herniation of spleen through a diaphragmatic rupture)
Review of Figure 4 shows that the spleen resides in its normal subdiaphragmatic position in the left upper quadrant and there is no evidence of diaphragmatic hernia. The solid, homogeneous nature of the lesion is consistent with a mesenchymal neoplasm, including sarcoma or desmoid tumor arising from the chest wall. A solitary fibrous tumor of the pleura is also a possibility, as is a lymphoproliferative lesion. Figure 7 shows a number of processes with an imaging appearance similar to the presented case.
Figure 6. Lesions / processes similar in appearance at imaging to the presented case: A. Intrathoracic splenic herniation following blunt abdominal trauma. B. Desmoid tumor of the anterior chest wall. C. Pseudotumor. D. Lymphoma. E. Fibrosarcoma arising from the pleural (calcification is evident). F. Sarcoma. G and H. Axial and sagittal images in a patient with solitary fibrous tumor of the pleura.
The percutaneous biopsy showed spindle cell tumor, with subsequent staining showing features consistent with aggressive fibromatosis / desmoid tumor.
Diagnosis: Aggressive fibromatosis / desmoid tumor.
Surgical consultation was conducted and the surgeon felt that surgery would not be efficacious given the potential for local recurrence after resection. Germ line testing was recommended, given the association of desmoid tumors with familial adenomatous polyposis syndrome. Treatment wit hormone manipulation, non-steroidal anti-inflammatory agents, and local cryoablation were planned in favor of radiation therapy.
References