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Cutaneous squamous cell carcinoma of the external auditory canal

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Cutaneous squamous cell carcinoma of the external auditory canal
Megan Nichole Bridges1, Mariana Doval MD FCAP2
Dermatology Online Journal 15 (2): 13

1. Medical Student at Kansas City University of Medicine and Biosciences. mbridges@kcumb.edu
2. Pathologist, Columbia Hospital, West Palm Beach, Florida


Abstract

Cutaneous squamous cell carcinoma (SCC) along with basal cell carcinoma (BCC), collectively known as Nonmelanoma skin cancer (NMSC), are the most common cancers in the United States. Squamous cell carcinoma of the skin is less common than BCC, but is known to be more aggressive with a higher mortality rate. Squamous cell carcinoma of the external auditory canal (EAC) is rare when compared to SCC on other cutaneous sites. Due to the rarity of SCC originating in the EAC, there is currently no universal staging system, making it difficult to analyze data and form a treatment strategy. This is a case of a 76-year-old man who initially presented with actinic keratosis of the EAC that died in just over a year from metastatic cutaneous SCC.



Introduction

Nonmelanoma skin cancer (NMSC) is the most common cancer in the United States with an incidence 18-20 times greater than that of malignant melanoma [1]. The estimated annual incidence is greater than one million cases per year [2]. The lifetime risks of developing NMSC were estimated to be 29 percent to 55 percent for basal cell carcinoma (BCC) and 7-11 percent for squamous cell carcinoma (SCC) [3]. Eighty percent of NMSC are BCC and 20 percent are SCC [4]. Cutaneous SCC is known to metastasize and grow more rapidly than the more common BCC [5,6]. This is a report of an elderly man with an original biopsy of hypertrophic actinic keratosis in the external auditory canal (EAC) that quickly became invasive SCC and ultimately led to his demise. In the nine months prior to receiving treatment, the tumor had replaced his right auricle, extended to the tympanic membrane, middle ear, right parotid lymph node, and the right lateral pterygoid muscle.


Case


Figure 1AFigure 1B
Figures 1A & 1B. Ulcerating and fungitating squamous cell carcinoma on presentation to the emergency department

A 76-year-old retired baker presented to a small community hospital's emergency department with a right ear malodorous mass that replaced his entire right auricle. The lesion appeared approximately nine months earlier in his external auditory canal and was initially 1.8 x 1.6 cm. The lesion was biopsied eight months prior to admission, which revealed changes compatible with the superficial portion of a hypertrophic actinic keratosis. He received Efudex (fluorouracil) on the lesion at the time of the original biopsy, but he never returned for his follow-up appointment scheduled one week later. The patient also had smaller lesions on his chin, nose, upper back, and right supra-clavicular region. The exudative right ear mass was bleeding at the time of presentation and was found to be superimposed with a Staphylococcus aureus infection (Figs. 1A & 1B). The tumor was evaluated to be T4, NX, MX, stage III, G2 and R2 [7]. Morphologically, the tumor showed dermal infiltration with irregular islands of well to moderately differentiated squamous cell carcinoma with focal prominent squamous pearl formation (Fig. 2A).


Figure 2AFigure 2B
Figure 2A. Irregular islands of well- to moderately-differentiated squamous cell carcinoma with focal prominent squamous pearl formation (H&E, x10)
Figure 2B. Focal mitotic activity with a desmoplastic response in the stroma (H&E, x40)

Focal mitotic activity was also noted and the stroma showed a desmoplastic response. Histologically, there was no evidence of angiolymphatic permeation (Fig. 2B). MRI and CT of the soft tissue of the head and neck as well as the brain with and without contrast revealed: a large right ear mass that extended along the tragus, antitragus, and had replaced the auricle and filled the external auditory canal. The mass extended to the tympanic membrane with thickening and probable atelectasis of the tympanic membrane as well as probable middle ear involvement. The ossicles were sclerotic on the right with generalized hyperostosis from this long-standing process. There was diffuse enhancement of this mass as well as ulceration and evidence of hemorrhage (Fig. 3).


Figure 3
Figure 3. Parasagittal T1 post-contrast MRI image through the right ear demonstrating enhancement and heterogeneity as well as focal areas of necrosis

Right parotid lymph node enlargement was noted, measuring 11 mm in maximum diameter. There was diffuse and extensive right mastoiditis. The mass also invaded the right lateral pterygoid muscle group and the massetor space on the right, which appeared to be contiguous. There was extension into the calvarium without evidence of intracranial extension. There was no sign of mass effect, shift, or hemorrhage and the brain was unremarkable for patient's age group (Fig. 4A & 4B).


Figure 4AFigure 4B
Figure 4A. Axial T2 MRI of the CP angle demonstrating a large helical and auricular fungitating cauliflower-like mass occupying the entire external auditory canal. There is no definitive diploic space involvement, but there is ispsilateral mastoiditis.
Figure 4B. Coronal post-contrast MRI through the mass in the plane of the dens. Demonstration of a large heterogeneously enhancing mass without involvement of the right temporal bone. There is normal enhancement of the left ear.

Tumor embolization was performed to help control bleeding before the patient was transferred to a large university hospital. There, the patient received a total auriclectomy (the resected area measuring approximately 8 cm x 11 cm) and a superficial parotidectomy sparing the facial nerve and its branches. He then had a lateral temporal bone resection followed by a deep lobe parotidectomy with resection of the lateral infratemporal fossa and a modified neck dissection (Fig. 5A). While the above procedures were being performed, the right arm was prepped and draped for removal of the radial forearm free flap to reconstruct the aforementioned defect (Fig. 5B). Each procedure was completed with no intraoperative complications. Following surgery, the patient was scheduled to receive post-operative radiation therapy which, at that time, was believed to stand a reasonable chance of being curative. Unfortunately, this patient's cancer had already metastasized and all further treatment was stopped because the patient was declared terminal. He died one year, one month, and a week after his original diagnosis of hypertrophic actinic keratosis.


Figure 5AFigure 5B
Figure 5A. Post resection of lesion
Figure 5B. Fore-arm free flap used to cover the defect.

Discussion

Most cases of cutaneous squamous cell carcinomas are easily treatable with an overall 5-year cure rate of > 90 percent [8] and a case fatality rate of only 1 percent [6]. Squamous cell carcinoma is the second most common malignancy of the skin occurring on the head and neck and is associated with a higher rate of metastasis than BCC. Tavin et al. reported a metastatic rate of 9.9 percent in their series of 387 patients with cutaneous SCC [9]. There are several predisposing conditions for SCC (Table 1) as well as factors associated with a poor prognosis (Table 2). Fortunately, there are several surgical and non-surgical treatment options currently available to treat cutaneous SCC, with Mohs Micrographic Surgery (MMS) shown to be the most effective treatment [4, 8]. The main advantage of MMS is the ability to examine 100 percent of the surgical margins, making incomplete excision less likely [62]. The cure rates reported for primary tumors treated with MMS were 93.3 percent and 94.8 percent [63, 64].

Our patient presented with invasive SCC that first began in the EAC. Carcinomas of the EAC occur each year in 1 of 5,000 to 15,000 patients with otologic disease [65]. SCC of the EAC is rare, with a prevalence of approximately one per million persons. Due to the rarity of these tumors, there is a lack of a universally accepted staging system, thus making it difficult to analyze data, formulate and evaluate a treatment strategy [66]. Preoperative clinical staging is difficult in these tumors because large parts of the temporal bone are not amenable to clinical examination [67]. Arriaga et al. [68] at the University of Pittsburgh, proposed a TNM staging system based on pre-therapeutic radiologic findings in CT scans and clinical examination (Table 3) [66, 67]. This staging system correlates well to the histopathologic tumor extension. From a surgical point of view, this system provides reliable and reproducible criteria for separating patients into TNM stages [66]. Depending on the stage of disease and treatment protocols, 5-year survival rates range from 10 percent for advanced disease to 83 percent for early disease [67]. The preferred treatment for cancer of the EAC and middle ear is radical surgery with tumor-free surgical margins and risk adapted postoperative radiotherapy [66, 67, 69]. The suggested surgery for complete resection of tumor of the EAC, middle ear, and temporal bone is a lateral temporal bone resection (resection of the bony external auditory canal, the tympanic membrane, the malleus and the incus with the medial limit of the incudostapedial joint), stage dependant, combined with a parotidectomy as well as a neck dissection [70, 71]. The most important survival factor is removal of the primary tumor with histologically clear margins [66, 67]. Pfreunder et al. found that the survival rate of patients with completely resected tumor was 100 percent, and of patients with tumor beyond surgical margins 66 percent at 5 years [67]. Moody et al. suggest that aggressive surgery for advanced tumors, especially those involving the dura, may not be in the patients' best interest, because prognosis remains poor with a 2-year survival of only 7 percent [72].

This patient's tumor initially presented as a small lesion of hypertrophic actinic keratosis in the external auditory canal. Within nine months, the lesion had completely replaced the right auricle, with extension to the tympanic membrane and the middle ear, as well as invasion into the right parotid lymph node and right lateral pterygoid muscle. Nine months after is original diagnosis, the patient underwent a right total auriclectomy, right parotidectomy, lateral temporal bone resection and a modified neck dissection followed by post-operative radiation. His treatment is consistent with several aforementioned studies which suggest that carcinoma of the external auditory canal and the middle ear should be treated by radical surgical excision and postoperative radiotherapy. For patients with advanced SCC (stages III and IV), such as this patient, incomplete resection can lead to recurrence despite post-operative radiation [73]. However, if our patient had returned to his follow-up appointment nine months prior, such drastic surgical measurements would not have been necessary and removal of the precursor lesion may have prevented his untimely death. In conclusion, a superficial biopsy read as actinic keratosis should not be disregarded, especially when found on high-risk areas such as the ear. Due to the possibility of malignant transformation of actinic keratosis to squamous cell carcinoma, these lesions should be treated appropriately and followed up with a repeat (deeper) biopsy if necessary in order to halt progression to a potentially lethal lesion.

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