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

Abstract

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.

An Update on Clinicopathological, Imaging and Genetic Features of Desmoplastic Fibroblastoma (Collagenous Fibroma)

“…We suggest that the enhancement pattern and the presence of a low signalintensity band may be useful to distinguish desmoplastic fibroblastoma and desmoid-type fibromatosis. To date, position-emission tomography features for desmoplastic fibroblastoma have been described in only two cases (9,10). Integrated positron-emission tomography/CT images show mild focal fluorodeoxyglucose uptake by the lesion, with a maximum standardized uptake value of 2.4 and 3.5, respectively.…”

An extremely rare case of desmoplastic fibroblastoma exhibiting rapid growth in the chest wall: a case report

“…The following fibrous tumors should be considered in the differential diagnosis of tumors occurring in the infrascapular region: desmoplastic fibroblastoma, desmoid-type fibromatosis, solitary fibrous tumor, and elastofibroma dorsi [9]. Among these tumor types, some of the imaging features of desmoplastic fibroblastoma are also common characteristics of desmoid-type fibromatosis, also called desmoid tumor [3][4][5][6][7]11]. CT scans typically reveal a well-defined inhomogeneous mass with a muscle-like density [13][14][15], without calcification or the presence of cystic lesions [3].…”

“…CT scans typically reveal a well-defined inhomogeneous mass with a muscle-like density [13][14][15], without calcification or the presence of cystic lesions [3]. MRI demonstrates findings of low-to iso-intensity to muscle on T1-weighted images, low-to slightly high-intensity or mixed-intensity on T2-weighted images, and heterogeneous enhancement on gadolinium-enhanced T1-weighted images with fat suppression [5][6][7]. Ultrasound reveals mixed echogenicity [5,6], and positron emission tomography reveals the diffuse uptake of fluorine-18 fluorodeoxyglucose [7].…”

“…Rim enhancement is considered to represent the abundant vascularity of the outer capsule-like fibrous tissue relative to that inside of the tumor [5,16]. However, the clinical utility of rim enhancement as an imaging feature remains limited, as certain characteristics are not fully understood [5][6][7]. For example, the capsule-like structure is a thin fibrous tissue, which appears dark and exhibits less enhancement on gadolinium-enhanced T1-weighted MR images [5][6][7], and abundant vascularity has been found inside of, but not around, the tumor by Doppler ultrasound [5].…”

“…Desmoplastic fibroblastomas share some features with other infiltrative tumors with fibrous components [3][4][5][6][7]; these other tumors are treated via surgical resection with a wide margin and exhibit high rates of local recurrence and metastasis [8]. Therefore, recognizing the unique characteristics of desmoplastic fibroblastoma is clinically important for the differential diagnosis of these tumors [3][4][5][6][7], although precise preoperative diagnosis remains challenging, mainly owing to the lack of established imaging features distinct to desmoplastic fibroblastoma [5][6][7].…”