Collagenous fibroma of the deltoid muscle: clinical, surgical and histopathological aspects

Computed tomography and magnetic resonance imaging findings in dogs with vaginal leiomyoma and leiomyosarcoma

BACKGROUND

In humans, magnetic resonance imaging (MRI) is preferred over computed tomography (CT) for the assessment of pelvic lesions. Although CT findings of several pelvic tumours have been reported in veterinary medicine, MRI findings are limited.

OBJECTIVES

The purpose of this study was to retrospectively compare the CT and MRI findings in dogs with vaginal leiomyoma and leiomyosarcoma.

METHODS

This retrospective study of five dogs compared the CT and MRI findings of intrapelvic lesions, including vaginal leiomyoma (n = 4) and leiomyosarcoma (n = 1). No invasion of the surrounding tissue was detected on histopathological examination. In this retrospective study, the following parameters of CT and MRI were recorded for each dog: the border between the lesion and the adjacent pelvic organs, including the prostate, rectum or urethra; signal intensity (SI) of the lesion; enhancement pattern; presence of haemorrhage; necrosis or cystic areas and lymphadenopathy. Because SI on MRI is affected by cell density, tumour cell density was analysed using a microscope slide.

RESULTS

In vaginal leiomyoma, the border between the lesion and the surrounding pelvic organ tends to be clearer on MRI than on CT. In vaginal leiomyosarcoma, the border was comparable between MRI and CT. Each lesion showed heterogeneous enhancement on CT and MRI scans. In each lesion, the assessment of haemorrhage, necrosis, cystic areas and lymphadenopathy was comparable between MRI and CT. The SI of the lesion on T2WI of the vaginal leiomyoma and leiomyosarcoma were hyperintense in four cases (4/4; 100%) and mixed intense in one case (1/1; 100%), respectively. The cell density of leiomyosarcoma is higher than that of leiomyomas.

CONCLUSIONS

The SI on T2WI may be useful for differentiating leiomyoma from leiomyosarcoma. MRI may be useful to differentiate vaginal leiomyomas from leiomyosarcomas and evaluate margins.

Multimodal radiological imaging of collagenous fibroma arising from the subacromial region in a patient with osteosarcoma: A case report

Collagenous fibroma arising from the subacromial region is extremely rare. It is important to distinguish collagenous fibroma from other fibrous tumors including desmoid tumors, to differentiate between the prognoses and management strategies, including surgical treatment. The present case report describes the case of a 42-year-old man with a collagenous fibroma of the subacromial region. He received a follow-up examination following treatment for osteosarcoma. Positron emission tomography (PET) scans used to assess for metastatic lesions indicated uptake in his left shoulder. The maximum standardized uptake value was 2.4. Magnetic resonance imaging demonstrated iso-intensity to muscle on T1-weighted images and iso-intensity with slightly high intensity on T2-weighted images. Post-contrast fat-suppressed magnetic resonance images indicated slightly heterogeneous enhancement of the lesion. There were no notable results from X-rays, bone scintigraphy and thallium-201 scintigraphy. Histological examination revealed collagenous fibroma. To the best of our knowledge, the present case is only the second incidence of collagenous fibroma arising from the subacromial region, and the first description of thallium-201 scintigraphy and PET scans in collagenous fibroma. The multimodal radiological data of this case may be useful for assisting in the differentiation of fibrous tumor types, including collagenous fibroma.