Case report: Evaluation of cutaneous squamous cell carcinoma metastasized to lymph nodes using 18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography in a dog

Introduction

18F-fluorodeoxy-2-deoxy-D-glucose (FDG) positron emission tomography (PET) is used with high sensitivity in human medicine for initial staging and treatment planning of cutaneous squamous cell carcinoma (SCC). To the best of our knowledge, 18F-FDG PET/computed tomography (CT) has not been used for canine cutaneous SCC with lymph node metastasis.

Case presentation

A 13 year-old spayed female Maltese had rapidly growing flank SCC, which had previously recurred twice. Radiography revealed no metastases. On PET/CT imaging, increased FDG uptake was observed not only in the flank but also in the left axillary lymph node and left inguinal lymph node (standardized uptake value max [SUVmax]: 8.602, 5.354, and 1.96, respectively). Despite the evidence of metastasis, palliative skin mass resection with a 3-cm margin and lymph node dissection were performed. Histopathological examination confirmed the presence of metastases in both lymph nodes.

Discussion

18F-FDG PET/CT is valuable for the detection of metastatic tumors in various organs. Cutaneous SCC can accumulate 18F-FDG, making it detectable on PET/CT. In this dog with flank SCC, 18F-FDG-PET/CT showed high SUVmax values, indicating its potential for tumor assessment. In veterinary medicine, SUVmax values of 2.5-3.5 are commonly used to identify metastatic lymph nodes in other cancers. Therefore, the interpretation of an SUVmax of 1.96 in an inguinal lymph node for metastatic involvement may be uncertain. Owing to the partial volume effect, 18F-FDG PET/CT has limited sensitivity in identifying LN metastases, particularly in cases of small lesions. Lower SUVmax values adjusted for smaller sizes may better distinguish between benign and malignant lymph nodes. Hence, combining differentiated SUVmax cut-offs based on lymph node size with CT assessment could enhance lymph node evaluation and assist in surgical planning.

Positron Emission Tomography/Computed Tomography Transformation of Oncology: Melanoma and Skin Malignancies

Skin cancers are the most common cancers, with melanoma resulting in the highest cause of death in this category. Accurate clinical, histologic, and imaging staging with fludeoxyglucose positron emission tomography (FDG PET) is most important to guide patient management. Whilst surgical excision with clear margins is the gold-standard treatment for primary cutaneous melanoma, targeted therapies have generated remarkable and rapid clinical responses in melanoma, for which FDG PET also plays an important role in assessment of treatment response and post-therapy surveillance. Non-FDG PET tracers, advanced PET technology, and PET radiomics may potentially change the landscape of the utilization of PET in the imaging of patients with cutaneous malignancies.

[The Cutaneous Squamous Cell Carcinoma - An Update]

BACKGROUND

The cutaneous squamous cell carcinoma (CSCC) is the second most common nonmelanoma skin cancer with an increasing incidence rate. Patients presenting with high-risk lesions associated with locally advanced or metastatic CSCC face high rates of recurrence and mortality.

METHODS

Selective literature review based on PubMed and consideration of current guidelines "Aktinische Keratosen und Plattenepithelkarzinom der Haut" and "Prävention von Hautkrebs".

FINDINGS

Complete surgical excision with histopathological control of excision margins is the gold standard in the treatment of primary CSCC. Radiotherapy can be used as an alternative treatment of inoperable CSCCs. In 2019, the PD1-antibody cemiplimab, has been approved for the treatment of locally advanced and metastatic CSCC by the European Medicines Agency. After 3 years of follow up, Cemiplimab shows overall response rates of 46 %, the median overall survival and median response rate had not been reached yet. Additional immunotherapeutics, combinations with other agents and oncolytic viruses are all potentially worth study to try, so clinical trial data will be forthcoming over the next few years to guide optimal use of these agents.

CONCLUSION

Multidisciplinary board decisions are mandatory for all patients with advanced disease who require more than surgery. Further development of existing therapeutic concepts, identification of new combination therapies and the development of new immunotherapeutics will be the key challenge over the next few years.

PET-CT in Clinical Adult Oncology-VI. Primary Cutaneous Cancer, Sarcomas and Neuroendocrine Tumors

PET-CT is an advanced imaging modality with many oncologic applications, including staging, therapeutic assessment, restaging and surveillance for recurrence. The goal of this series of six review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for specific oncologic indications, the potential pitfalls and nuances that characterize these applications, and guidelines for image interpretation. Tumor-specific clinical information and representative PET-CT images are provided. The current, sixth article in this series addresses PET-CT in an evaluation of aggressive cutaneous malignancies, sarcomas and neuroendocrine tumors. A discussion of the role of FDG PET for all types of tumors in these categories is beyond the scope of this review. Rather, this article focuses on the most common malignancies in adult patients encountered in clinical practice. It also focuses on Food and Drug Agency (FDA)-approved and clinically available radiopharmaceuticals rather than research tracers or those requiring a local cyclotron. This information will serve as a guide to primary providers for the appropriate role of PET-CT in managing patients with cutaneous malignancies, sarcomas and neuroendocrine tumors. The nuances of PET-CT interpretation as a practical guide for imaging providers, including radiologists, nuclear medicine physicians and their trainees, are also addressed.

[Diagnostics and treatment of secondary malignancies of the parotid gland-An overview]

BACKGROUND

Secondary malignancies of the parotid gland frequently have a cutaneous origin and the incidence in central Europe is increasing.

OBJECTIVE

The aim of this review article was to present the epidemiology, (differential) diagnostics and treatment of secondary malignancies of the parotid gland.

MATERIAL AND METHODS

A literature search of the current guidelines and evidence was carried out in the web-based databank PubMed.

RESULTS

The incidence of secondary malignancies of the parotid gland seems to be increasing in Europe, mainly due to a rising incidence of metastases of cutaneous squamous cell carcinomas. Except for malignant lymphomas, parotidectomy is the treatment of choice in the curative situation. In the absence of clear evidence, in the case of an intact facial nerve lateral or total parotidectomy with ipsilateral neck dissection seems to be indicated, depending on the entity of the secondary malignancy.

CONCLUSION

The differential diagnostics of squamous cell carcinoma (in) of the parotid gland can be complicated. When a squamous cell carcinoma of the parotid gland is diagnosed for the first time, a dermatological full body examination and a detailed medical history should be taken with respect to skin tumors of the head and neck region. In addition to surgical treatment of the parotid gland and neck, adjuvant radiotherapy is usually indicated.

Das kutane Plattenepithelkarzinom – ein Update

Hintergrund Das kutane Plattenepithelkarzinom (PEK) ist nach dem Basalzellkarzinom der zweithäufigste bösartige Hauttumor. In Deutschland wurden 2014 über 50.000 PEK-Neuerkrankungen dokumentiert. Mit Zunahme der durchschnittlichen Lebenserwartung und Komorbiditäten treten mittlerweile auch gehäuft lokal fortgeschrittene Tumore mit Metastasierung auf.

Methode Selektive Literaturrecherche in PubMed und unter Berücksichtigung der deutschen S3-Leitlinien „Aktinische Keratosen und Plattenepithelkarzinom der Haut“ und „Prävention von Hautkrebs“.

Ergebnisse Beim PEK ist der Goldstandard die vollständige Exzision des Primärtumors mittels histopathologischer Kontrolle der Schnittränder. Eine Radiotherapie kann eingesetzt werden, wenn eine vollständige Exzision nicht erreicht werden kann bzw. Inoperabilität besteht. Im Falle eines metastasierten (mPEK) oder lokal fortgeschrittenen (laPEK) PEK, welches nicht kurativ operiert oder bestrahlt werden kann, werden systemische medikamentöse Therapien eingesetzt. Mit der Zulassung des PD1-Antikörpers Cemiplimab steht seit 2019 in der EU eine neue systemische Therapie zur Behandlung des fortgeschrittenen PEK zur Verfügung. Nach bis zu 3 Jahren Follow-up sprechen noch 46% der Patienten mit mPEK und laPEK auf Cemiplimab an, der Medianwert für das Gesamtüberleben und die Ansprechdauer ist in beiden Gruppe noch nicht erreicht. Weitere Antikörper gegen PD1 oder PDL1, Kombinationstherapien sowie die Immuntherapie mit onkolytischen Viren ermöglichen zahlreiche Therapieoptionen und sind aktuell Gegenstand der Forschung.

Schlussfolgerung Mit der Zunahme von fortgeschrittenen Stadien des PEK nimmt die Wichtigkeit des interdisziplinären Tumorboards für den Therapieentscheid immer mehr zu. Die Weiterentwicklung bestehender therapeutischer Konzepte, die Identifikation von gut wirksamen Kombinationstherapien sowie die Entwicklung weiterer verträglicher zielgerichteter Systemtherapien ist eine entscheidende dermatoonkologische Herausforderung der nächsten Jahre.

A Novel Radiotherapeutic Approach to Treat Bulky Metastases Even From Cutaneous Squamous Cell Carcinoma: Its Rationale and a Look at the Reliability of the Linear-Quadratic Model to Explain Its Radiobiological Effects

Introduction

Metastatic cutaneous squamous cell carcinoma (cSCC) is a very rare condition. The lack of definition of an oligometastatic subgroup means that there is no consensus for its treatment, unlike the mucosal head and neck counterpart. Like the latter, the cutaneous form is able to develop bulky tumor masses. When this happens, the classic care approach is just for palliative intent due to a likely unfavorable benefit–risk balance typical of aggressive treatments. Here we proposed a novel radiotherapy (RT) technique to treat bulky metastases from cSCC in the context of an overall limited tumor burden and tried to explain its clinical outcome by the currently available mathematical radiobiological and ad hoc developed models.

Methods

We treated a case of facial cSCC with three metastases: two of them by classic stereotactic RT and the other by lattice RT supported by metabolic imaging (¹⁸F-FDG PET) due to its excessively large dimensions. For the latter lesion, we compared four treatment plans with different RT techniques in order to define the best approach in terms of normal tissue complication probability (NTCP) and tumor control probability (TCP). Moreover, we developed an ad hoc mathematical radiobiological model that could fit better with the characteristics of heterogeneity of this bulky metastasis for which, indeed, a segmentation of normoxic, hypoxic, and necrotic subvolumes might have been assumed.

Results

We observed a clinical complete response in all three disease sites; the bulky metastasis actually regressed more rapidly than the other two treated by stereotactic RT. For the large lesion, NTCP predictions were good for all four different plans but even significantly better for the lattice RT plan. Neither the classic TCP nor the ad hoc developed radiobiological models could be totally adequate to explain the reported outcome. This finding might support a key role of the host immune system.

Conclusions

PET-guided lattice RT might be safe and effective for the treatment of bulky lesions from cSCC. There might be some need for complex mathematical radiobiological models that are able to take into account any immune system’s role in order to explain the possible mechanisms of the tumor response to radiation and the relevant key points to enhance it.

Clinical value of 18F-FDG-PET/CT in staging cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin malignancy. Computed tomography (CT) and/or MRI are commonly used for staging, however, the role of fluorine-18-fluorodeoxyglucose (F-FDG)-PET is not clearly established. In this study, we evaluated F-FDG-PET/CT imaging for initial staging of cSCC.

PATIENTS AND METHODS

F-FDG-PET/CT scans performed in patients with newly diagnosed cSCC were reviewed retrospectively. Images were visually assessed for lesions and F-FDG uptake [standardized uptake value (SUV)] in primary and secondary sites was measured. Suspected lesions on F-FDG-PET/CT were correlated with histopathology when available, follow-up imaging or clinical data in others.

RESULTS

Twenty-three cSCC patients who underwent F-FDG-PET/CT at diagnosis were evaluated. Primary sites were in head/neck (n=21), chest (n=1), and foot (n=1). All patients had F-FDG-positive scans with a total of 51 F-FDG-positive lesions. All primary lesions (n=24) were F-FDG-positive (SUV: 2.3-22.8; mean 10.2), and additional 27 F-FDG-positive lesions, including 21 nodes, four cutaneous, one osseous and one lung lesion, were noted in 13 patients. Mean size of F-FDG-positive nodes was 0.9 cm (range: 0.4-2.5 cm), predominantly clinically impalpable. Pathology was available for 40/51 lesions; 31 sites positive for malignancy. SUV (mean±SD) was 9.2±6.2 for malignant and 2.7±1.2 for benign lesions. Sensitivity, positive predictive value, and accuracy of F-FDG-PET/CT scan were 100, 77.5, and 77.5%, respectively. F-FDG detected seven additional lesions in three patients, compared to CT/MRI. Overall, staging F-FDG-PET/CT detected nine prior unknown lesions in five patients that were proven metastatic disease by histopathology or follow-up; F-FDG-PET/CT modified management in 5/23 (21.7%) patients.

CONCLUSION

F-FDG-PET/CT has high sensitivity in the detection of cSCC lesions, including small cutaneous and nodal disease, and has a potential role in initial staging and management.