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ORIGINAL ARTICLE
Year : 2022  |  Volume : 18  |  Issue : 2  |  Page : 476-481

Imaging features of dermatofibrosarcoma protuberans


1 Department of Radiology, Qilu Hospital of Shandong University (Qingdao), Qingdao, China
2 Department of Healthcare, Qilu Hospital of Shandong University (Qingdao), Qingdao, China
3 Department of Radiology, Huangdao District Central Hospital, Qingdao, China

Date of Submission15-Sep-2021
Date of Decision01-Feb-2022
Date of Acceptance11-Feb-2022
Date of Web Publication20-May-2022

Correspondence Address:
Jiuwen Li
Department of Healthcare, Qilu Hospital of Shandong University (Qingdao), Qingdao - 266035
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcrt.jcrt_1619_21

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 > Abstract 


Aims: The study highlights diffusion-weighted imaging (DWI) and dynamic enhancement features of DFSP and characterizes unenhanced and enhanced computed tomography (CT) and magnetic resonance imaging (MRI) scans.
Settings and Design: Image findings and clinical histories of 23 patients with DFSP were reviewed. Nine patients underwent CT before and after intravenous administration of contrast material. MRI was performed for 17 patients. CT and MRI findings were analyzed using location, size, edge, shape, infiltration sign, density and signal enhancement mode, and degree.
Results: Patients showed 26 superficial and one deep lesion. Ten superficial lesions bulged onto the skin surface. Fourteen lesions were well-defined and 13 ill-defined. All lesions were nodular, with nine being multilobular. Thirteen showed infiltration to adjacent skin, fat, and fascia. Seven lesions on CT were iso- or hypo-dense to muscle without calcification. Contrast-enhanced CT showed inhomogeneous moderate and progressive enhancement in the arterial phase. Small tortuous vessels were seen in the arterial phase in one case. Sixteen tumors displayed signals that were similar to muscle by T1WI. Ten lesions were either hyper-intense to muscle or iso-intense to fat; the deep DFSP was hypo-intense by T2WI. All lesions were hyper-intense homogeneously or heterogeneously under fat-suppressed T2WI. Twelve superficial lesions showed high-intermediate signal, and one deep lesion showed low-intermediate signal with DWI. Seven cases showed low signal diffusion coefficient (ADC) images. Dynamic enhancement and signal intensity-time (SI-T) curves of four tumors showed rapid SI increases followed by steady or slightly rising SI. All lesions showed inhomogeneous, progressive enhancement in the arterial phase.
Conclusions: This report is the first on dynamic curves and highlights DWI and T2WI features of DFSP. DFSP can be correctly diagnosed by combining a patient's clinical manifestations with imaging characteristics.

Keywords: Computed tomography, dermatofibrosarcoma protuberans, DWI, MRI, signal intensity-time curve


How to cite this article:
Ren Q, Li J, Shangguan J, Feng X, Ma X. Imaging features of dermatofibrosarcoma protuberans. J Can Res Ther 2022;18:476-81

How to cite this URL:
Ren Q, Li J, Shangguan J, Feng X, Ma X. Imaging features of dermatofibrosarcoma protuberans. J Can Res Ther [serial online] 2022 [cited 2022 Jul 7];18:476-81. Available from: https://www.cancerjournal.net/text.asp?2022/18/2/476/345528




 > Introduction Top


Dermatofibrosarcoma protuberans (DFSP) is a rare, low-malignancy soft tissue tumor that occurs mainly in the dermis and subcutaneous mesenchymal tissues. It accounts for about 6% of soft tissue sarcomas.[1] These tumors are clinically similar, but treatment schemes are different. DFSP grows by infiltration and tends to recur after surgery.[2] The imaging features of DFSP are helpful for diagnosis, selection of surgical methods, and reduction of recurrence.[3],[4] Most published studies focused on the characteristics of DFSP by using computed tomography (CT) and magnetic resonance imaging (MRI). Few studies report the characteristics of DFSP on diffusion-weighted imaging (DWI) and dynamic contrast enhancement (DCE). This study analyzes radiologic images of 23 patients with proven DFSP retrospectively to evaluate imaging characteristics of DFSP comprehensively and highlights DWI and DCE features and their pathological basis.


 > Subjects and Methods Top


Images and medical histories of 23 patients were reviewed. Nine patients had CT scans before and after intravenous administration of contrast material. MRI was performed for 17 patients by using 1.5T or 3.0T MRI systems. Sixteen patients had unenhanced MRI: 16 with T1-weighted imaging (T1WI, TR = 500–700 ms, TE = 10–18 ms), 10 with T2-weighted imaging (T2WI, TR = 1800–4500 ms, TE = 70–90 ms), 15 with fat-suppressed T2WI (TR = 1800–4500 ms, TE = 70–90 ms), 11 with DWI (TR = 7000 ms, TE = 80 ms, diffusion sensitivity coefficient (b) values were 0, 1000 s/mm2), and 7 with apparent diffusion coefficient (ADC) images. 8 patients had enhanced MRI: 4 with dynamic and delayed enhanced MRI after intravenous administration of gadolinium (dose: 0.2 mL/kg, injection rate: 3 mL/s) and another four patients with only delayed enhanced MRI.

CT and MRI findings were analyzed by two independent experienced radiologists for the location, size, edge, shape, infiltrative sign, density and signal, and enhancement mode and degree. When the two radiologists had different diagnoses, a final diagnosis was reached by consensus.

Pathological data included diagnoses and immunohistochemical analyses.


 > Results Top


Patients included 14 men and 9 women aged 5–72 years (mean = 38.4 years; median = 36.0 years). Eighteen cases were primary, and five cases were recurrent. Thirteen tumors occurred in the torso, seven in the limbs, two in the head, and one in the breast. The most common sign was slowly enlarging firm nodules or masses (n = 13). Twelve cases reported red or purple-to-red lesion surfaces, and seven patients reported recent local pain. The course of the disease was 5 months–20 years. Recurrences of DFSP occurred, on average, 30 months after primary tumor resection (SD: 25.4, Min.: 5, Max.: 72).

Twenty-three patients displayed 27 nodular lesions: 11 tumors were singular [Figure 1], nine were coalescent [Figure 2] and [Figure 3], and two were multiple but separated (both showed three nodules). One patient had two separate nodules; one nodule was excluded from the study based on biopsy results. Twenty-six of 27 lesions were superficial, occurring in the dermis or subcutaneously [Figure 1], [Figure 2], [Figure 3]. One lesion was deep in the fascia [Figure 4]. Ten superficial lesions bulged onto the skin surface, showing an exogenous growth pattern [Figure 1], [Figure 2], [Figure 3]. The size of tumors ranged from 0.5 to 9.8 cm. Fourteen lesions were well-defined [Figure 1], [Figure 2], [Figure 3], and 13 were ill-defined, including five recurrent tumors, four of which exhibited peripheral edema [Figure 5]. Thirteen tumors had infiltrated into adjacent skin (n = 9) [Figure 1]c, fat (n = 6) [Figure 3]b, and fascia (n = 3) [Figure 5]d.
Figure 1: DFSP in a 43-year-old male overlying the left anterior chest wall with a Ki-67 positive index of 30% by immunohistochemistry. The mass (long arrows) shows moderate inhomogeneous enhancement in the arterial phase (a), density gradually increases in venous (b) and delayed phases (c) showing a progressive enhancement pattern. Small tortuous vessels are noted in the arterial phase (arrowhead-a). The mass infiltrates adjacent skin (arrowheads-c)

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Figure 2: DFSP in a 32-year-old female with a mass protruding from the anterior abdominal wall. (a) Axial T2WI shows a well-defined multilobular mass with two coalescent nodules (arrow), which is nearly iso-intense to fat. The mass displays high SI on DWI (b) and slightly low SI on ADC images (c). The mass shows exophytic growth (arrows). DCE-curve shows an early peak, then remains steady or slightly rising (d). The lesion shows inhomogeneous marked enhancement in the arterial phase and inhomogeneous hyper-intensity in the delayed phase (e)

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Figure 3: DFSP of the leg in a 47-year-old man with a mass that slowly enlarged over 20 years. (a) Axial T1WI shows a well-defined, homogeneous soft tissue mass on the inner side of the thigh (arrow), which is iso-intense to muscle. (b) The mass is exophytic and multilobular with coalescent nodules infiltrating fat on sagittal fat-suppressed T2WI (arrowhead). (c) DWI shows the mass with high signal intensity

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Figure 4: DFSP in a 5-year-old boy with a swelling in the right frontal scalp. The mass (long arrows) is deep and affects the skull external lamina (arrowhead-a). The lesion is iso-intense to muscle on T1WI (b) and inhomogeneously iso-intense to muscle on T2WI (a). It shows low-intermediate SI on DWI (c)

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Figure 5: Recurrent DFSP in a 46-year-old male with a lump on the back where DFSP was resected 8 years prior. The mass is ill-defined (arrows), showing peripheral edema (arrowhead-a) and fat and fascia infiltration (arrowhead-d). The lesion enhances progressively with an area of non-enhancement (delta-c, d). The tumor is hypo-intense on pre-contrast suppressed T1WI (delta-b) and markedly hyperintense on sagittal fat-suppressed T2WI (delta-a), corresponding to an area of low density on CT (delta-e)

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CT scan findings

Unenhanced CT scans found seven lesions that were iso- or hypo-dense to muscle, of which six were homogeneous. One recurrent lesion showed a region of decreased attenuation [Figure 5]e. No evidence of calcification was observed in any patient. Contrast-enhanced CT scans of three tumors showed inhomogeneous moderate enhancement in the arterial phase and gradually increasing density in venous and delayed phases. These images showed a progressive enhancement pattern, and one case displayed small tortuous vessels in the arterial phase [Figure 1]a.

MRI findings

Sixteen patients with 20 lesions underwent T1WI. Signals for all lesions were similar to the muscle. Nineteen lesions were homogeneous [Figure 3]a, and one recurrent lesion showed a region of lower signal [Figure 5]b. Ten patients with 10 lesions underwent T2WI. Lesions were either hyper-intense to the muscle (n = 5) or even iso-intense to fat (n = 4) [Figure 2]a. The only deep DFSP was hypo-intense to muscle [Figure 4]a. Fifteen patients with 19 lesions underwent fat-suppressed T2WI. Ten lesions showed homogeneous high signals, and nine lesions were heterogeneous with relatively low interior signals [Figure 3]b. Eleven patients with 13 lesions underwent DWI. Twelve superficial lesions showed high signals [Figure 2]b and [Figure 3]c, and the one deep lesion showed a low-intermediate signal [Figure 4]c. Nine lesions in seven patients had ADC images and showed low signals [Figure 2]c. Four patients underwent DCE MRI. Signal intensity-time (SI-T) curves showed rapid SI increases to a peak followed by steady or slightly rising intensity [Figure 2]d. All lesions displayed inhomogeneous marked enhancement in the arterial phase [Figure 2]e. Signals increased with time. Eight showed inhomogeneous hyper-intensity in the delayed phase [Figure 2]e. The recurrent case exhibited a non-enhanced area corresponding to the lower signal region on pre-contrast T1WI [Figure 5].

Pathological results

Twenty-three patients were diagnosed with DFSP. Tumor cells were abundant and arranged in fascicular and mat-like patterns. Immunohistochemical analysis showed that all tumors were CD34+ with Ki-67 positive indices of 5%–40%.


 > Discussion Top


DFSP is the most common superficial soft tissue mesenchymal tumor. The 2020 WHO soft tissue tumor classification categorizes DFSP as an intermediate (locally aggressive) fibroblastoma/myofibroblastic tumor.[5] Pathogenesis is still unclear and may be related to trauma, genetics, radiation damage, or other factors.[6] DFSP is common in middle-aged patients with a peak incidence at 30–50 years of age. The ratio of male to female patients is 3:2.[6],[7] The disease can occur anywhere on the body but most commonly on the torso and limbs. Occurrence is rarely on the head, neck, or breast.[6],[7],[8] Study patients were consistent with the above characteristics. Pathologically, DFSP infiltrates and grows along the dermis and invades adjacent fat, fascia, and even muscle. It is prone to recur after surgery but rarely metastasizes.[9] Microscopically, spindle cells arrange densely around collagen fibers and blood vessels. Immunohistochemically, 80%–100% of DFSP is CD34+.[6],[8] Genetically, DFSP is associated with rearrangement of chromosomes 7 and 22 and fusion of platelet-derived growth factor β-chain and α-chain-type 1 collagen genes.[6],[10]

The DFSP is generally superficial and originates from the dermis or subcutaneously. Tumors are closely connected with the skin. The disease may involve adjacent skin and form a skin tail. A superficial lesion involving the skin is a strong indicator of DFSP.[8],[11] One lesion in the present study was located deep in the fascia. Torreggiani et al.[7] reported that about 30% of DFSP is deep, but DFSP in other literature is all superficial. DFSP is nodular with either singular or multiple coalescent nodules, presenting a multilobular appearance. Some authors believe that the shape of multiple coalescent nodules is a defining characteristic of DFSP,[1],[6],[12] but only 33.33% (9/27) of lesions in our study were multilobular. DFSP mostly grows exogenously, extending to the skin surface and erupting outside. This feature is an important characteristic that distinguishes DFSP from other superficial tumors. This characteristic was found in 45.45% (10/22) of primary DFSPs in the current study. Most primary (14/22) DFSPs were well-defined, except at their infiltrating edge, and all recurrent lesions were ill-defined with edema seen in ~80% (4/5) of recurrences. Imaging findings of recurrent DFSP were similar to primary lesions as reported in the literature.[2]

DFSP grows aggressively with infiltration manifesting as bands on the edge of the tumor and extending into the adjacent skin, fat, and fascia tissue on CT/MRI scans.[1],[6],[8],[13],[14] Density, signal, and enhancement mode of infiltrations are similar in DFSP and are pathological manifestations. In the present study, 48.15% (13/27) of the lesions showed infiltration. These signs can help physicians plan for an appropriate surgical scope and may reduce postoperative recurrence.

Unenhanced CT images displayed a density of DFSP that was slightly lower than or equal to that of the muscle, and no calcification was found. These observations are similar to a previous report.[8] Primary lesions were usually homogeneous and recurrences heterogeneous. On MRI, the lesion was T1-iso-intense to muscle, often hyper-intense to the muscle, and even iso-intense to the fat on T2WI.[6],[7],[8] Study cases are consistent with this feature; most lesions were intermediate or hyper-intense on T2WI.

Four study cases underwent DCE MRI; SI-T curves showed early peaks followed by steady or slightly rising intensity. This finding is consistent with type B or C curves and reflects low malignancy.[15] This report is the first, to our knowledge, on the DCE MRI features of DFSP. DFSP showed an inhomogeneous marked enhancement in the arterial phase. The density/signal of lesions gradually increased with time, showing progressive enhancement. This phenomenon has not been widely reported. Zhang et al.[8] reported only one case of a CT multiphase enhanced scan showing prolonged, delayed enhancement. DFSP showed homogeneous or heterogeneous moderate or marked enhancement.[6],[7],[8] in the delayed phase, consistent with the present results. Moderate or marked enhancement in the arterial phase is related to the rich blood supply to DFSP.[12],[16] Prolonged enhancement in areas with abundant tumor cell components and areas with a low degree of enhancement in delayed enhancement mode may be associated with collagen components.[8],[17] Conversely, areas without enhancement might reflect cystic degeneration, necrosis, or hemorrhage.[17] One case with CT enhancement in study patients showed small tortuous vessels in the arterial phase. Choong et al.[11] reported that DFSP with fibrosarcomatous transformation was more prone to flow voids on T2WI. This patient's Ki-67 positive index was 30%, indicating a relatively high degree of malignancy.[18] Perhaps an increase in small vessels is a sign of malignancy for DFSP tumors.

DWI findings of DFSP are rarely reported. All superficial DFSPs in the present study showed high signals on DWI and slightly lower signals on ADC images. Only the deep scalp lesion showed a low-intermediate signal. Limited reports on DWI for DFSP present similar results.[4] DWI reflects the ability of water molecules to diffuse. The denser the tumor cells, the fewer water molecules diffuse, and DWI signal intensity is increased. DFSP is a cell-rich tumor.[4] characterized by high signal on DWI and low signal on ADC images. The diffusion of water molecules in DFSP is related to cell components and collagen content.[19] Greater collagen content promotes water diffusion and leads to higher ADC and lower DWI signal intensity.[19],[20] However, collagen content in DFSP is decreased.[21] Thus, the high DWI signal intensity of DFSP is also due to decreases in internal collagen.

The decrease in collagen in DFSP may also be a reason for high SI on T2WI. Collagen can shorten T2 relaxation time[22] and produce low signals on T2WI. Less collagen will thus increase T2 relaxation time. Therefore, unlike other fibrous tumors with T2-hypointensity, DSFP shows higher SI on T2WI. Choong et al.[11] reported that the T2 signal intensity reduced when DFSP transformed to fibrosarcoma. T2 signal intensity of nine superficial DFSPs in study patients were all higher than muscle; four lesions were even T2-iso-intense to fat, and only the deep lesion was T2-iso-intense to the muscle. We speculate that the relatively high SI on T2WI is a characteristic of DFSP and may also reflect its lower malignancy potential, as does the SI-T curve.

DFSP is a soft tissue tumor that occurs in superficial locations. Superficial lesions originate from skin, subcutaneous tissue, or fascia[1] and should be diagnosed with different combinations of clinical manifestations and imaging characteristics. Lipoma and liposarcoma exhibit typical fat SI and are easily differentiated from DFSP. In addition, DFSP often occurs in the torso, but dermatofibroma usually occurs in the limbs. SI of the latter on T2WI is often low.[1] Neurogenic tumors often grow along nerves with mixed SI. Hemangioma often shows calcification on CT and is T1-hypo-intense and T2-hyper-intense on MRI. Skin epidermoid cysts also show high SI on DWI but are round and well-defined without infiltration. These cysts rarely protrude from the skin surface and show no enhancement. Nodular fasciitis often arises in the fascial layer and most often occurs in the upper extremities.

The present study has some limitations associated with retrospective analysis. MRI was performed without a standard protocol. ADC values were not intended for correlation with Ki-67 status. DCE MRI and DWI features are described but correlated with different pathological types of DFSP.

In conclusion, this report is the first on dynamic curves and highlights DWI and T2WI features of DFSP. DFSP can be correctly diagnosed by combining the patient's clinical manifestations with imaging characteristics.

Ethical approval

This article does not contain any studies with human participants performed by any of the authors.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Financial support and sponsorship

This research was supported by the Qingdao Key Health Discipline Development Fund, the National Key Research and Development Program of China (2016YFC0105901SDZ), the Qingdao Science and Technology Demonstration and Guidance Project (20-3-4-37-nsh), and the Flexible Talent Project of Qilu Hospital of Shandong University (Qingdao) (QDKY2019RX05 and QDKY2019RX13).

Conflicts of interest

There are no conflicts of interest.



 
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