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What Is Your Diagnosis?

What Is Your Diagnosis?

Wilmer A. Lopez Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL

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Jordan C. Ayers Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL

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Judith Bertran Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL

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 DVM, MS, DACVS
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Stacey A. Fox-Alvarez Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL

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Federico R. Vilaplana Grosso Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL

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 LV, DECVDI, DACVR
DOI:
https://doi.org/10.2460/javma.22.06.0260
Volume/Issue:
Volume 261: Issue 1
Online Publication Date:
17 Aug 2022
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History

A 2-year-old 39.7-kg sexually intact female Rhodesian Ridgeback was presented for evaluation of an acute-onset of lethargy. On initial examination, the patient was febrile (rectal temperature, 39.4 °C; reference range, 37.8 to 39.2 °C). A large, firm abdominal mass was palpated in the mid to caudal aspect of the abdomen, and palpation of it elicited signs of discomfort. A CBC revealed moderate leukocytosis (36 × 103 WBCs/μL; reference range, 5.0 × 103 to 13.0 × 103 WBCs/μL) characterized by mild to moderate neutrophilia (30 × 103 neutrophils/μL; reference range, 2.7 × 103 to 8.9 × 103 neutrophils/μL) and moderate monocytosis (3.38 × 103 monocytes/μL; reference range, 0.1 × 103 to 0.8 × 103 monocytes/μL). A serum biochemical panel showed mild hyperglobulinemia (5.1 g/dL; reference range, 2.5 to 4.5 g/dL) and mildly high alkaline phosphatase activity (264 U/L; reference range, 23 to 212 U/L). Three-view abdominal radiographic images were obtained (Figure 1).

Figure 1
Figure 1
Figure 1
Figure 1

Left lateral (A), right lateral (B), and ventrodorsal (C) composite abdominal radiographic images of a 2-year-lod 39.7-kg sexually intact female Rhodesian Ridgeback evaluated because of an acute onseset of lethargy.

Citation: Journal of the American Veterinary Medical Association 261, 1; 10.2460/javma.22.06.0260

Diagnostic Imaging Findings and Interpretation

Abdominal radiography revealed a large (approx 20 × 25 × 20 cm [length × width × height]), well-defined, ovoid mass in the midventral aspect of the abdomen. The mass was smoothly marginated but slightly lobulated and was heterogeneously soft tissue opaque, with associated internal amorphous, striated, and nodular mineral opacities. The resultant mass effect displaced the small and large intestines peripherally. Within the retroperitoneum, there was a moderate increase in wispy soft tissue striations, causing a decrease in the retroperitoneal detail, compatible with effusion (Figure 2). Based on the location, origin of the mass effect, and radiographic appearance of the mass, differential diagnosis for this midventral abdominal mass with mineralization included neoplastic etiologies, mineralized granulomatous lesions (particularly with the dog’s young age), and, less likely, a cyst, hematoma, or abscess from either ovarian, uterine, mesenteric, lymph node, or gastrointestinal tissue origin. A less likely neoplastic differential diagnosis was peritoneal extraskeletal osteosarcoma, and another nonneoplastic differential diagnosis was gossypiboma; however, no history of prior abdominal surgery was reported.

Figure 2
Figure 2
Figure 2
Figure 2

Same images as Figure 1. There is a large, well-defined, ovoid, smoothly marginated but slightly caudally lobulated, heterogeneously soft tissue opaque mass (white arrowheads) that has internal amorphous, striated, and somewhat nodular mineral opacities. The mass displaces the small and large intestines peripherally. Within the retroperitoneum, there are wispy soft tissue striations and a loss of detail (asterisk).

Citation: Journal of the American Veterinary Medical Association 261, 1; 10.2460/javma.22.06.0260

Triple-phase (ie, arterial, portal, and delayed venous phases) contrast-enhanced abdominal CT was performed and revealed a 17.2 × 13.5 × 13.1-cm, well-defined, smoothly marginated, ovoid mass associated with the right ovary in the left midventral aspect of the abdomen. The mass was homogeneously fluid attenuating cranially and had a caudal area of heterogenous, lobular mixture of fat (approx –95 HU), fluid (approx 15 HU), soft tissue (approx 35 HU), and mineral (approx 1,100 HU) attenuating tissue. The mass had a thin, peripheral, soft tissue–attenuating, mildly contrast-enhancing capsule. The soft tissue–attenuating regions of the mass showed mild to moderate heterogenous contrast enhancement. Scant peritoneal effusion and moderate retroperitoneal effusion was noted. Multiple retroperitoneal (renal and aortic) lymph nodes were moderately to severely enlarged, with ill-defined, rounded margins, heterogeneous attenuation, and poor, heterogeneous contrast enhancement. The largest lymph node measured 8.7 × 3.5 × 3.3 cm. These enlarged nodes resulted in severe compression of the caudal vena cava and poor vascular perfusion caudal to the site of compression. Multiple other lymph nodes, including the medial iliac, internal iliac, sacral, jejunal, and superficial inguinal lymph nodes, were mildly enlarged and had heterogenous contrast enhancement (Figure 3).

Figure 3
Figure 3
Figure 3
Figure 3

Precontrast transverse plane (A) and portal vascular phase postcontrast transverse (B) and dorsal (C) plane abdominal CT images of the dog described in Figure 1. The mass (17.2 × 13.5 × 13.1 cm; arrowheads) is heterogeneously attenuating; is surrounded by a thin peripheral soft tissue–attenuating, mildly contrast-enhancing capsule; and causes dorsolateral displacement of the left ovary and right-sided and dorsal displacement of the intestine. Enlarged renal and aortic lymph nodes compress the caudal vena cava (dashed arrow). The images are displayed in a soft tissue window (window width, 400 HU; window level, 40 HU) with a 3-mm slice thickness. C—The dashed line represents the orthogonal image plane. The dog’s right side is toward the left in all images.

Citation: Journal of the American Veterinary Medical Association 261, 1; 10.2460/javma.22.06.0260

On thoracic CT, throughout the pulmonary parenchyma, there were a few small soft tissue–attenuating foci and a larger soft tissue–attenuating nodule (diameter, 0.15 cm) located in the accessory lung lobe (not shown). With the inclusion of CT imaging, the updated primary differential diagnosis for the right ovarian mass was malignant neoplasia of germ cell origin (eg, dysgerminoma, teratocarcinoma, and teratoma), with metastatic lymphadenopathy of the renal and aortic lymph nodes, severe associated caudal vena cava compression, and suspected early pulmonary metastatic disease. The other multifocal mild lymphadenopathy was believed to be reactive.

Treatment and Outcome

A fine-needle aspirate of the ovarian mass was obtained for cytologic analysis and was interpreted by the clinical pathologist as malignant neoplasm of suspected undifferentiated blast cells or embryonal glomeruli origin. The owner elected at-home hospice care, and the patient was discharged with a prescription of piroxicam (0.3 mg/kg, PO, q 12 h).

Five months later, the owner reported that the patient was doing well at home and was still receiving piroxicam (0.3 mg/kg, PO, q 12 h). Follow-up CT of the thorax, abdomen, and pelvis revealed that the right ovarian mass was smaller (15.3 × 12.5 × 10.5 cm), had progressive fat and mineral attenuation, and had markedly decreased fluid attenuation. There was resolution of the retroperitoneal effusion; retroperitoneal, peritoneal, and peripheral lymphadenopathy; and caudal vena cava compression (Supplementary Figure S1). Additionally, the pulmonary nodules had resolved (not shown). The patient underwent an exploratory laparotomy and ovariohysterectomy, and findings on histologic evaluation were consistent with mature teratoma of the right ovary. No evidence of disease was found on 3-view thoracic radiography or abdominal ultrasonography performed 6 months later. The patient has remained clinically well, and the owner’s plans to continue piroxicam lifelong and repeated imaging on a biannual basis.

Comments

The dog of the present report had an uncommonly encountered ovarian neoplasm. A mature teratoma is a germ cell neoplasm that is composed of at least 2 or more well-differentiated embryonic tissues and germ cell layers (ie, mesoderm, ectoderm, and endoderm).1,2 Primary ovarian tumors are infrequent and believed to represent < 10% of all ovarian neoplasms.1,2 One case series1 describing teratomas in 7 dogs reported a median age of 4 years (range, 2 to 9 years) at the time of diagnosis, with 3 of the 7 dogs having evidence of metastasis at time of presentation. Something important to note is that the histologic phenotype of the masses in all 3 dogs with metastatic disease was immature, poorly differentiated, or both.1 Still, good long-term outcomes have been reported following ovariectomy or ovariohysterectomy in canine patients with localized ovarian disease.1,3

For the dog of the present report, we observed an ovarian tumor that displayed radiographic features of mineralization, similar to previously reported cases of mature teratomas.1 The mineral opacities and other radiographic features of the ovarian teratoma in our patient were consistent with the structures evident on histopathology (eg, bone, cartilage, dermal adnexa, and odontogenic tissue). We argue that due to the varied composition of each ovarian teratoma, radiographic appearances differ based the composition and differentiation of the germ cell layers present. For example, mature ovarian teratomas with well-differentiated mesodermal layers may contain radiographically mineral opacities due to the presence of mesodermal-derived structures such as teeth, bone, and cartilage, whereas other mature ovarian teratomas that may only have endodermal or ectodermal tissues may appear uniformly soft tissue opaque on radiography. This may potentially make radiographic diagnosis challenging.

The imaging findings for the retroperitoneum of our patient were compatible with retroperitoneal effusion. We reason that the retroperitoneal effusion was secondary to the lymphadenomegaly compressing the caudal vena cava, inflammation associated with the lymphadenopathy, or both and not from the ovarian tumor itself, because in canines, the ovaries reside within the peritoneal cavity. This concept is also important as it directly corresponds with the mass effect noted on radiography, where the intestines were displaced caudally and slightly dorsally, suggesting the mass originated from a peritoneal structure as opposed to one in the retroperitoneum. Without this concept, we would have not been able to accurately formulate a list of possible tissue origins and radiographic differential diagnoses for the mass.

This report also described a rare ovarian tumor in a young dog with imaging findings most consistent with disseminated metastasis that underwent substantial regression, downstaging the patient to the point where surgical excision of the primary tumor was achievable; a situation that, to our knowledge, has not previously been described. A potential rationale for this could have been that the ovarian teratoma itself, its cystic components, or both were causing a severe inflammatory reaction that improved with the use of an NSAID (ie, piroxicam in this case). NSAIDs can also have antiangiogenic and antineoplastic properties and have been used as a treatment for certain tumor types.4 This supported another theory that the teratoma was actually aggressive and responded to piroxicam, which acted as an antineoplastic agent.

Abdominal radiography helped us prioritize neoplastic disease for the dog of the present report; however, the use of CT was vital for determining the mass’s composition (fat, soft tissue, and mineral) and confirming its ovarian origin. This was crucial to the formulation of the differential diagnosis list and aided in the inclusion of an ovarian teratoma in the described differential diagnoses. For ovarian teratomas, presumptive diagnosis cannot be made via radiography alone, and both CT and histopathology play crucial roles in the diagnosis of mature ovarian teratomas.1,2

Supplementary Materials

Supplementary materials are posted online at the journal website: avmajournals.avma.org

Acknowledgments

No external funding was used in this case. The authors declare that there were no conflicts of interest.

References

  • 1. ↑

    Greenlee PG, Patnaik AK. Canine ovarian tumors of germ cell origin. Vet Pathol. 1985;22(2):117–122.

  • 2. ↑

    Sforna M, Brachelente C, Lepri E, Mechelli L. Canine ovarian tumours: a retrospective study of 49 cases. Vet Res Commun. 2003;27(suppl 1):359–361.

  • 3. ↑

    Jergens AE, Knapp DW, Shaw DP. Ovarian teratoma in a bitch. J Am Vet Med Assoc. 1987;191(1):81–83.

  • 4. ↑

    Thun MJ, Henley SJ, Patrono C. Nonsteroidal anti-inflammatory drugs as anticancer agents: mechanistic, pharmacologic, and clinical issues. JNCI J Natl Cancer Inst. 2002;94(4):252–266.

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Supplementary Materials

Contributor Notes

Corresponding author: Dr. Vilaplana Grosso (fvilaplanagrosso@ufl.edu)

In collaboration with the American College of Veterinary Radiology

Cover Journal of the American Veterinary Medical Association
Journal of the American Veterinary Medical Association
Publication Date:
17 Aug 2022
  • Figure 1 Figure 1 Figure 1
    View in gallery
    Figure 1

    Left lateral (A), right lateral (B), and ventrodorsal (C) composite abdominal radiographic images of a 2-year-lod 39.7-kg sexually intact female Rhodesian Ridgeback evaluated because of an acute onseset of lethargy.

  • Figure 2 Figure 2 Figure 2
    View in gallery
    Figure 2

    Same images as Figure 1. There is a large, well-defined, ovoid, smoothly marginated but slightly caudally lobulated, heterogeneously soft tissue opaque mass (white arrowheads) that has internal amorphous, striated, and somewhat nodular mineral opacities. The mass displaces the small and large intestines peripherally. Within the retroperitoneum, there are wispy soft tissue striations and a loss of detail (asterisk).

  • Figure 3 Figure 3 Figure 3
    View in gallery
    Figure 3

    Precontrast transverse plane (A) and portal vascular phase postcontrast transverse (B) and dorsal (C) plane abdominal CT images of the dog described in Figure 1. The mass (17.2 × 13.5 × 13.1 cm; arrowheads) is heterogeneously attenuating; is surrounded by a thin peripheral soft tissue–attenuating, mildly contrast-enhancing capsule; and causes dorsolateral displacement of the left ovary and right-sided and dorsal displacement of the intestine. Enlarged renal and aortic lymph nodes compress the caudal vena cava (dashed arrow). The images are displayed in a soft tissue window (window width, 400 HU; window level, 40 HU) with a 3-mm slice thickness. C—The dashed line represents the orthogonal image plane. The dog’s right side is toward the left in all images.

Figure 1

Left lateral (A), right lateral (B), and ventrodorsal (C) composite abdominal radiographic images of a 2-year-lod 39.7-kg sexually intact female Rhodesian Ridgeback evaluated because of an acute onseset of lethargy.
Figure 1

Left lateral (A), right lateral (B), and ventrodorsal (C) composite abdominal radiographic images of a 2-year-lod 39.7-kg sexually intact female Rhodesian Ridgeback evaluated because of an acute onseset of lethargy.
Figure 1

Left lateral (A), right lateral (B), and ventrodorsal (C) composite abdominal radiographic images of a 2-year-lod 39.7-kg sexually intact female Rhodesian Ridgeback evaluated because of an acute onseset of lethargy.
Figure 2

Same images as Figure 1. There is a large, well-defined, ovoid, smoothly marginated but slightly caudally lobulated, heterogeneously soft tissue opaque mass (white arrowheads) that has internal amorphous, striated, and somewhat nodular mineral opacities. The mass displaces the small and large intestines peripherally. Within the retroperitoneum, there are wispy soft tissue striations and a loss of detail (asterisk).
Figure 2

Same images as Figure 1. There is a large, well-defined, ovoid, smoothly marginated but slightly caudally lobulated, heterogeneously soft tissue opaque mass (white arrowheads) that has internal amorphous, striated, and somewhat nodular mineral opacities. The mass displaces the small and large intestines peripherally. Within the retroperitoneum, there are wispy soft tissue striations and a loss of detail (asterisk).
Figure 2

Same images as Figure 1. There is a large, well-defined, ovoid, smoothly marginated but slightly caudally lobulated, heterogeneously soft tissue opaque mass (white arrowheads) that has internal amorphous, striated, and somewhat nodular mineral opacities. The mass displaces the small and large intestines peripherally. Within the retroperitoneum, there are wispy soft tissue striations and a loss of detail (asterisk).
Figure 3

Precontrast transverse plane (A) and portal vascular phase postcontrast transverse (B) and dorsal (C) plane abdominal CT images of the dog described in Figure 1. The mass (17.2 × 13.5 × 13.1 cm; arrowheads) is heterogeneously attenuating; is surrounded by a thin peripheral soft tissue–attenuating, mildly contrast-enhancing capsule; and causes dorsolateral displacement of the left ovary and right-sided and dorsal displacement of the intestine. Enlarged renal and aortic lymph nodes compress the caudal vena cava (dashed arrow). The images are displayed in a soft tissue window (window width, 400 HU; window level, 40 HU) with a 3-mm slice thickness. C—The dashed line represents the orthogonal image plane. The dog’s right side is toward the left in all images.
Figure 3

Precontrast transverse plane (A) and portal vascular phase postcontrast transverse (B) and dorsal (C) plane abdominal CT images of the dog described in Figure 1. The mass (17.2 × 13.5 × 13.1 cm; arrowheads) is heterogeneously attenuating; is surrounded by a thin peripheral soft tissue–attenuating, mildly contrast-enhancing capsule; and causes dorsolateral displacement of the left ovary and right-sided and dorsal displacement of the intestine. Enlarged renal and aortic lymph nodes compress the caudal vena cava (dashed arrow). The images are displayed in a soft tissue window (window width, 400 HU; window level, 40 HU) with a 3-mm slice thickness. C—The dashed line represents the orthogonal image plane. The dog’s right side is toward the left in all images.
Figure 3

Precontrast transverse plane (A) and portal vascular phase postcontrast transverse (B) and dorsal (C) plane abdominal CT images of the dog described in Figure 1. The mass (17.2 × 13.5 × 13.1 cm; arrowheads) is heterogeneously attenuating; is surrounded by a thin peripheral soft tissue–attenuating, mildly contrast-enhancing capsule; and causes dorsolateral displacement of the left ovary and right-sided and dorsal displacement of the intestine. Enlarged renal and aortic lymph nodes compress the caudal vena cava (dashed arrow). The images are displayed in a soft tissue window (window width, 400 HU; window level, 40 HU) with a 3-mm slice thickness. C—The dashed line represents the orthogonal image plane. The dog’s right side is toward the left in all images.
  • 1.

    Greenlee PG, Patnaik AK. Canine ovarian tumors of germ cell origin. Vet Pathol. 1985;22(2):117–122.

  • 2.

    Sforna M, Brachelente C, Lepri E, Mechelli L. Canine ovarian tumours: a retrospective study of 49 cases. Vet Res Commun. 2003;27(suppl 1):359–361.

  • 3.

    Jergens AE, Knapp DW, Shaw DP. Ovarian teratoma in a bitch. J Am Vet Med Assoc. 1987;191(1):81–83.

  • 4.

    Thun MJ, Henley SJ, Patrono C. Nonsteroidal anti-inflammatory drugs as anticancer agents: mechanistic, pharmacologic, and clinical issues. JNCI J Natl Cancer Inst. 2002;94(4):252–266.

    • PubMed
    • Search Google Scholar
    • Export Citation

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