Maxillary OCC Mimicking Nonhealing Extraction Sockets

Abstract and Introduction

Abstract

Background: Carcinoma cuniculatum is a rare variant of squamous cell carcinoma, mostly affecting the skin but also sparsely reported to occur in the oral cavity. Oral carcinoma cuniculatum (OCC) tends to be misdiagnosed as verrucous carcinoma; this may lead to inadequate treatment and recurrence due to the locally aggressive nature of the tumor. This report presents the case of a 56-year-old man with a progressively enlarging painful OCC at the maxillary right molar region, exhibiting both exophytic (red, soft, nodular mass) and endophytic (superficial ulceration and bone exposure, mimicking nonhealing extraction sockets) growth patterns. Incisional biopsy was consistent with OCC, a diagnosis that was corroborated through histopathologic examination of the resected specimen. The patient underwent en bloc resection (segmental maxillectomy) of the tumor and prosthetic rehabilitation with an obturator and remains disease-free 2.5 years postoperatively.

Conclusions: The aim of this report is to provide a thorough clinical imaging and histopathological presentation of OCC along with a brief literature review to highlight the difficulties of accurate diagnosis and the pitfalls in treating this uncommon entity.

Introduction

Oral carcinoma cuniculatum (OCC) is a rare variant of oral squamous cell carcinoma (OSCC) that possesses similar clinicopathological findings and clinical course with cutaneous carcinoma cuniculatum, first described and reported^[1] to involve various sites (ie, face, esophagus, abdomen, lower extremities, penis, and cervix). Flieger and Owinski (1977) were the first to report OCC^[2] without establishing an association with OSCC, mainly because of its distinct histological architecture (well-differentiated epithelium without or with minimal atypia) and less aggressive behavior.

According to both the 2005 and 2017 World Health Organization (WHO) classifications of tumors, OCC represents a rare, independent, locally aggressive subtype of OSCC. OCC is characterized by keratin-filled branching crypts and keratin cores like rabbit burrows (hence the term "cuniculatum" from the Latin word for rabbit), lined by well-differentiated, hyperplastic, stratified squamous epithelium with minimal atypia, extending deep into the connective tissue and potentially invading adjacent bone that only rarely induces nodal or distant metastases.^[3,4]

The diagnosis of OCC remains challenging because of clinicians' lack of familiarity with this entity, leading to underdiagnosis and a deceptively low incidence.^[5] The correlation of histopathological findings with clinical and radiological features is crucial to its diagnosis and differentiation from other histological subtypes of OSCC, such as verrucous carcinoma (VC) and papillary OSCC.^[5] Misdiagnosis of OCC as VC is reportedly common, due to not only overlapping clinical features (papillomatous keratinized surface) but also inadequate (superficial and/or non-representative) sampling during biopsy; however, given the local aggressiveness of OCC and particularly its propensity to invade bone, misdiagnosis as VC may lead to inadequate treatment and local recurrence.^[4–6]

The objective of this article is to present the authors' experience in treating an interesting case of OCC, affecting the posterior maxilla of a 56-year-old male patient. Furthermore, a review of the literature has been conducted to illustrate the clinical features, imaging and histopathological findings, treatment strategies, and overall biological behavior of this rare subtype of OSCC, with the goal of optimizing diagnostic and therapeutic decisions.