Spontaneous Tumor Regression of Squamous Cell Carcinoma of Scalp, Case Report

Abstract

A 91-year-old Colombian man with squamous cell carcinoma of the frontal scalp region with a clinical and histopathological diagnosis, associated with a locoregional metastasis in the left submandibular lymph node, treated by surgical resection of the primary lesion and cervical dissection, however, the primary tumor had regressed spontaneously. Clinical Trial Registration Not applicable.

Introduction

The head and neck region are frequently affected by primary cancers, with approximately 500,000 new cases globally each year [1, 2]. Cutaneous squamous cell carcinoma (SCC) has specific risk factors including skin type, sun exposure, age, and immunosuppression. Immunosuppressed individuals, especially solid organ transplant recipients, face a 65- to 100-fold higher risk of developing cutaneous SCC [2]. Around 2% of cutaneous SCCs can metastasize [3]. Spontaneous regression, defined as a tumor’s partial or complete disappearance without treatment [4], is estimated at one in 60,000-100,000 cancer cases [5, 6]. Spontaneous regression in head and neck cancers is rare, often triggered by immune responses and changes in the tumor microenvironment [7]. Certain cancers, like testicular germ cell tumors and neuroblastoma, show higher frequencies of spontaneous regression [8]. This document discusses a rare instance of spontaneous regression in a SCC on the frontal scalp, adding to the limited literature on such occurrences.

Case

A 91-year-old man presents to the head and neck surgery clinic with an oncological diagnosis of moderately-differentiated infiltrating squamous cell carcinoma (SCC) of the scalp. The physical examination revealed an exophytic lesion measuring 40 × 30 mm, no palpable lymph nodes. Ultrasound was performed and identified one submaxillary nodal suspicious in the left side, a fine needle aspiration cytology was done and confirmed malignity (Fig. 1). It was considered T3N1M0 stage III [9].

Fig. 1.

Initial scalp biopsy; A. SCC of the frontal scalp region; B. Left submaxillary nodal confirmed by FNA malignity 9 × 1.6 mm; C. SCC initial biopsy, Hematoxylin-eosin stain. 4X low power vision; D. Hematoxylin-eosin stain 10X; E. Hematoxylin-eosin stain, perineural invasion 10X; F. Immunohistochemistry nuclear staining with P40 at 10X

8 weeks after the initial SCC diagnostic, without any treatment, the primary tumor suffered a SR. The residual scar area was resected with perilesional oncological margins of 8 mm and left supraomohyoid lymph node dissection. Pathology results reported negative for residual squamous cell type neoplastic lesion. In the resected lymph node, metastatic squamous cell carcinoma (1/11) with a tumor focusses of 13 × 10 mm. Given the atypical presentation of the case, a review of the biopsy slides and immunohistochemistry of the p16 cervical lymph node were requested, it was negative (Fig. 2). After 6 months of follow-up, the patient is disease free.

Fig. 2.

Wide local scalp resection and cervical dissection. A. 8 weeks after the initial diagnosis; B. Full thickness skin with representation of hypodermic fat, fibrosis, without evidence of tumor lesion 4X; C. Actinic damage to the dermis and fibrosis, without evidence of tumor 4X; D. Involutional fibrosis of the full thickness of the dermis with extension to hypodermic fat 10X; E. Lymph node with metastatic tumor involvement due to squamous cell carcinoma 4X; F. Metastatic tumor squamous morulae, surrounded by lymphoid tissue 10X

Discussion

Spontaneous tumor regression has been frequently re-defined depending on the type of cancer in the last century, however, is commonly known as a partial or complete disappearance of primary tumor tissue or its metastases in patients who have never received treatment [7]. According to previous research, certain tumor types rarely regress, whereas others, such as testicular germ cell tumors and neuroblastoma, regress with a certain frequency [8]. The rate of spontaneous regression for SCC is still unknown.

There has been much speculation as to the mechanisms of spontaneous regression, however, nowadays, this phenomenon is believed to be caused the activation of apoptosis caused by a series of events in the immune system and tumor microenvironment [7]. Due to the increased incidence of malignancies observed in patients that are immunosuppressed, and considering in vitro and in vivo evidence, an immunologic mechanism has been proposed. Changes in the apoptotic pathways of SCC have been suggested as a mechanism for both carcinogenesis and spontaneous regression, potentially mediated by T cell-induced apoptosis. Cytotoxic T lymphocytes (CTLs) and Natural Killer cells (NK) possess the ability to detect and trigger apoptosis in cancer cells. Current immunotherapy approaches primarily rely on CTLs. Nevertheless, there is growing recognition of the crucial role Helper T cells (HTLs) play in prompting tumor remission. Apoptosis is a factor that can be important, but it is part of an internal process since the cell cannot be externally modified [8]. Another factor that might be involved in some cases of spontaneous regression is the trophic effects from hormones on cancerous cells [10].

In this report we present the case of a patient with a lesion on the scalp that presented a typical clinical presentation and histopathological findings that favor a moderately-differentiated infiltrating SCC with spontaneous tumor regression. The review of the pathology demonstrated moderately differentiated neoplastic proliferation of keratinocytes, with involvement of the epidermis, superficial, middle and deep reticular dermis, immunohistochemistry with positive CK5/6, P40, P63, CD45, findings consistent with SCC. CK7, CK20 negative, removing the possibility of metastatic infiltration. After the resection, pathology results reported negative for residual squamous cell type neoplastic lesion in the scalp area.

In our case, the patient had metastatic lymph node involvement, and it has been documented that the cancerous cells that access the lymph nodes, aside from being partially blocked, notably stimulate the immune system. Cases of spontaneous regression of lymph node metastases of carcinoma have been reported [8].

There are few reported cases in the literature of spontaneous tumor regression of SCC; nonetheless, to our knowledge this is the first spontaneous regression of SCC of the skin with lymph node involvement documented.

Although the currently most accepted theory of this type of tumor is regression associated with an immunological response, there is still much to understand about the exact mechanisms involved.

Conclusion

This is a case of spontaneous tumor regression evidenced in a SCC of the scalp. As reviewed, there are few cases reported in the literature. It is necessary to highlight the importance of the immune system as a possible factor associated with this phenomenon. It is proposed that lymph node tumor involvement could also be associated with a possible immune activator. Cases like this are important to learn more about the events associated with this process in this type of cancer.

Declarations

Ethical Approval

To report this case (or case series) was obtained from Research Ethics Committee of Clínica Imbanaco (CEI-901).

External Financing

No.

Patient Consent

Was obtained.

Permission to Reproduce Material from Other Sources

Not applicable.

Conflict of Interest

None.