Imaging findings of cutaneous angiosarcoma of the scalp: Comparison with cutaneous squamous cell carcinoma

Significantly Elevated FDG Activity in Neurothekeoma

ABSTRACT

Neurothekeoma is a very rare cutaneous lesion affecting mainly young patients. The lesion is generally benign. We report here that intense FDG activity on PET/CT was noted at the site of primary neurothekeoma of the right shoulder in a 16-year-old boy. Abnormal FDG activity was also seen in the metastatic neurothekeoma in the lung in the same patient 2 years later.

Management of Non-Melanoma Skin Cancer: Radiologists Challenging and Risk Assessment

Basal cell carcinoma, squamous cell carcinoma, and Merkel cell carcinoma are the three main types of nonmelanoma skin cancers and their rates of occurrence and mortality have been steadily rising over the past few decades. For radiologists, it is still difficult to treat patients with advanced nonmelanoma skin cancer. Nonmelanoma skin cancer patients would benefit greatly from an improved diagnostic imaging-based risk stratification and staging method that takes into account patient characteristics. The risk is especially elevated among those who previously received systemic treatment or phototherapy. Systemic treatments, including biologic therapies and methotrexate (MTX), are effective in managing immune-mediated diseases; however, they may increase susceptibility to NMSC due to immunosuppression or other factors. Risk stratification and staging tools are crucial in treatment planning and prognostic evaluation. PET/CT appears more sensitive and superior to CT and MRI for nodal and distant metastasis as well as in surveillance after surgery. The patient treatment response improved with advent and utilization of immunotherapy and different immune-specific criteria are established to standardized evaluation criteria of clinical trials but none of them have been utilized routinely with immunotherapy. The advent of immunotherapy has also arisen new critical issues for radiologists, such as atypical response pattern, pseudo-progression, as well as immune-related adverse events that require early identification to optimize and improve patient prognosis and management. It is important for radiologists to have knowledge of the radiologic features site of the tumor, clinical stage, histological subtype, and any high-risk features to assess immunotherapy treatment response and immune-related adverse events.

Prognostic value of 18F-FDG PET/CT and MRI features in patients with high-risk and very-high-risk cutaneous squamous cell carcinoma

Objective:

This study aimed to evaluate the prognostic value of 18F-fludeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and MRI features in patients with high-risk and very-high-risk cutaneous squamous cell carcinoma (cSCC).

Methods:

This study included 54 consecutive patients with surgically resected primary high-risk and very-high-risk cSCC who underwent pre-operative FDG-PET/CT and/or MRI. Among them, 14 patients (26%) had recurrences. We retrospectively reviewed the FDG-PET/CT (n = 34) and MRI (n = 48) and investigated the clinical significance and prognostic value of imaging features in cSCC.

Results:

On FDG-PET/CT, the maximum standardized uptake value (SUVmax) of the primary tumor (13.0 ± 6.4 vs. 6.9 ± 5.3, p < 0.05) was higher in cSCC with recurrence than in cSCC without recurrence. On MRI, the maximum diameter of the lesion (46.8 ± 24.1 mm vs 30.4 ± 17.0 mm, p < 0.05) and the frequency of muscle/tendon/bone invasion (42% vs 11%, p < 0.05) were significantly greater in cSCC with recurrence than in cSCC without recurrence. In the univariate analysis, prognostic factors for recurrence were SUVmax of the primary tumor (p < 0.01), the maximum diameter of the lesion (p < 0.05), and depth of invasion (p < 0.05). The areas under the receiver operating characteristic curves of the SUVmax (0.78) were superior to those of the maximum diameter (0.71) and depth of invasion (0.60).

Conclusion:

SUVmax, maximum diameter, and depth of invasion were useful parameters for prognostic factors predicting recurrence in patients with high-risk and very-high-risk cSCC.

Advances in knowledge:

SUVmax represents a prognostic factor.

Imaging findings of malignant skin tumors: radiological-pathological correlation

Sometimes, radiologists encounter malignant skin tumors (MSTs) during image interpretation. As MSTs require different clinical management modalities for each histological subtype, accurate preoperative diagnosis is essential. The histological subtypes of MST can be easily assessed by visual inspection or biopsy. Therefore, the significant role of radiological imaging in MSTs is to evaluate the extent of local invasion, nodal involvement, and distant metastasis, and the histological estimation of MSTs by radiological imaging has not been reported until a few years ago. However, recent studies have revealed characteristic radiological features for differential diagnosis of MSTs, such as configuration, intratumoral homogeneity, signal intensity, cyst formation, and hemorrhage. Other important clinical data for determining the histological subtype of MST include age, gender, and site of occurrence. MSTs can be categorized as epidermal, melanocytic, adnexal, and mesenchymal tumors based on the origin and have distinctive characteristics. Hence, this review article was designed to describe the clinical and radiological features of MSTs.

Assessing the accuracy of computed tomography in detecting bony invasion and thickness of squamous cell carcinoma of the scalp

OBJECTIVES

The aim of this study was to ascertain the accuracy of computed tomography (CT) in assessing the presence of bony involvement and thickness of squamous cell carcinoma (SCC) of the scalp.

METHODS

A single-centre retrospective chart review was carried out. Inclusion criteria were scalp SCC, CT between January 2008 and 2018, and the availability of a reference test. Reference tests were either histology, surgical notes or clinical notes. Tabular assessment of accuracy was performed and Student's t-test, Mann-Whitney U test and Fisher exact test were used in univariable analysis. Accuracy of thickness measurement was calculated using the limits of agreement method, and linear regression was used to examine trend.

RESULTS

Thirty-nine patients were included. Most patients were male (74.4%), white (97.4%), not immunosuppressed (66.6%) and had poorly differentiated tumours (33.3%). The most common tumour sites were the vertex (28.2%) and temporal region (23.1%). Sensitivity of CT in detecting presence or absence of bony invasion of scalp SCC was 76.9% (95% CI 46.2-94.9%) and specificity was 96.2% (95% CI 80.4-99.9%). Overall accuracy was 89.7% (95% CI 75.8-97.1%), positive predictive value was 90.1% (95% CI 58.7-99.8%) and negative predictive value was 89.3% (95% CI 71.8-97.7%). No significant differences were found comparing patients with an accurate or inaccurate CT scan. Thickness on CT was found to be consistent with histological thickness at the 95% confidence level.

CONCLUSIONS

CT is accurate at assessing the presence of bony involvement and thickness of scalp SCC. This study was limited somewhat by small sample size.

Imaging findings of trichilemmal cyst and proliferating trichilemmal tumour

PURPOSE

The purpose of this study was to evaluate computed tomography and magnetic resonance imaging of benign trichilemmal cysts and proliferating trichilemmal tumours.

METHODS

Nineteen histologically confirmed cutaneous lesions with trichilemmal keratinisation (12 trichilemmal cysts and seven proliferating trichilemmal tumours) were enrolled. Among them, 10 lesions (six trichilemmal cysts and four proliferating trichilemmal tumours) were examined by computed tomography, while 13 lesions (eight trichilemmal cysts and five proliferating trichilemmal tumours) were examined by magnetic resonance imaging. Computed tomography and magnetic resonance imaging characteristics were retrospectively reviewed.

RESULTS

Sixteen lesions (84%, 10 trichilemmal cysts and six proliferating trichilemmal tumours) occurred on the scalp. Lobulated margins were observed in five lesions (26%, three trichilemmal cysts and two proliferating trichilemmal tumours). With respect to computed tomography attenuation, calcification (>200 Hounsfield units) was observed in seven lesions (70%, five trichilemmal cysts and two proliferating trichilemmal tumours), hyperdense areas (≥80 and ≤200 Hounsfield units) in six (60%, three trichilemmal cysts and three proliferating trichilemmal tumours), and soft tissue density areas (<80 Hounsfield units) in nine (90%, five trichilemmal cysts and four proliferating trichilemmal tumours). On T1-weighted images, intratumoral hyperintensity was only observed in eight trichilemmal cysts but no proliferating trichilemmal tumours (100% vs. 0%, P<0.01). On T2-weighted images, hypointense rim and intratumoral hypointensity was observed in all 13 lesions (100%, eight trichilemmal cysts and five proliferating trichilemmal tumours), and linear or reticular hypointensity was observed in 10 (77%, six trichilemmal cysts and four proliferating trichilemmal tumours).

CONCLUSION

Trichilemmal cysts and proliferating trichilemmal tumours predominantly occurred on the scalp with calcification, and usually exhibited linear or reticular T2 hypointensity. Intratumoral T1 hyperintensity may be a useful imaging feature for differentiating trichilemmal cysts from proliferating trichilemmal tumours.