Jeongyun Jeong, Jupill Chang, Seunghee Lee, Soeun An, Kyuchang Kim, Min Su Lee, Ji Young Yhee, Jaehwan Kim, Kidong Eom
Background
Diaphragmatic tumors are exceedingly rare in veterinary medicine, with only a few cases of sarcomas previously documented. This report describes the first known instance of a diaphragmatic well-differentiated liposarcoma in a dog, emphasizing the computed tomographic (CT) characteristics that distinguished it from more common differentials such as hernia, granuloma, or hepatic mass.
Methods
A 9-year-old neutered male Chihuahua was referred for assessment of a suspected diaphragmatic hernia. Radiographs and abdominal ultrasound provided inconclusive findings, prompting a contrast-enhanced CT scan performed under general anesthesia. Imaging parameters included 120 kVp, 150 mA, 1 mm slice thickness, and pre- and postcontrast acquisitions with iohexol. Surgical excision and histopathologic evaluation followed CT diagnosis.
Results
CT revealed a 1.83 × 1.98 × 2.63 cm soft-tissue-attenuating mass bulging cranially into the left caudal thorax with smooth, continuous borders contiguous with the diaphragm. The mass compressed the adjacent liver and contained multifocal hypoattenuating lesions (minimum −22 HU), suggestive of mixed fat and soft tissue composition. No lymphadenopathy or metastasis was observed. Surgical excision confirmed a firm, tan-white mass arising from the diaphragm without phrenic nerve or vascular involvement. Histopathology demonstrated proliferating well-differentiated adipocytes and lipid-laden mesenchymal tumor cells, confirming a well-differentiated liposarcoma. Resection margins were tumor-free.
Limitations
As a single case report, these findings cannot define the full CT spectrum of canine diaphragmatic liposarcomas. The absence of immunohistochemical or molecular profiling limits subtype classification beyond histologic assessment. Additionally, follow-up data on long-term recurrence or metastasis were not provided.
Conclusions
This case identifies a unique presentation of a well-differentiated liposarcoma originating from the diaphragm in a dog, characterized on CT by a well-defined diaphragmatic mass with mixed fat and soft tissue attenuation and hepatic compression. Recognition of smooth diaphragmatic continuity and heterogeneous fat composition may aid in differentiating diaphragmatic liposarcomas from hernias or hepatic masses. Further research is needed to establish imaging patterns across liposarcoma subtypes in veterinary patients
Precontrast (A) and postcontrast (B) CT images in the transverse plane and precontrast (C) and postcontrast (D) CT images in the dorsal plane. (A, B) A soft tissue attenuating mass (asterisk) bulging cranially into the left caudal thorax and compressing the left medial lobe (arrow) is visible. Heterogeneous tumor parenchyma, along with multifocal hypoattenuating lesions (arrowheads), is visible in both precontrast and postcontrast images. (C, D) Multifocal hypoattenuating lesions (arrowheads) are well demonstrated in the precontrast images. Point Hounsfield Unit measurements revealed a minimum value of −22 HU. The mass (asterisk) exhibits a well-defined margin and a smooth, continuous border with the adjacent left diaphragm (dotted arrow).
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