Gingival Carcinoma Cuniculatum: A Case Series of Seven Cases with Emphasis on Immunohistochemical and Histochemical Features

Oral carcinoma cuniculatum (CC) is a rare distinct variant of oral squamous cell carcinoma (OSCC) displaying unique clinical and histopathological features. CC is a locally aggressive malignancy with lower metastatic potential and has a tendency to invade the underlying bone yielding nonspecific clinical presentation resembling fungal/bacterial infections or osteomyelitis. Seven rare cases of gingival CC are reported with special emphasis on immunohistochemistry and special stains. Clinical and demographic profile were analysed and all cases were subjected to Ki-67 and p53 immunostaining and Ayoub-Shklar histochemical staining. For comparison, age and gender matched seven cases of conventional OSCC with bony involvement were recruited. IBM SPSS statistics software version 26 (IBM Analytics, Armonk, New York, U.S.) was used to analyse the data. All cases of CC lacked p53 expression in contrast to OSCC and demonstrated intermediate to high proliferation index in stroma also. The keratin staining and cytokeratin profile in OSCC and CC were also found to be statistically different. CC is a rare well differentiated variant of OSCC with different pathways involved in the pathogenesis. Local aggressive and invasive nature could be the result of unique interaction between epithelium and stromal elements. Oral health care provider must be familiar with this uncommon variant of OSCC.

Oral carcinoma cuniculatum, a rare variant of squamous cell carcinoma

INTRODUCTION

Carcinoma cuniculatum (CC) is a rare variant of squamous cell carcinoma (SCC). Lack of awareness of this tumor and its difficult diagnosis delay management and complicate treatment. The aim of this study is to describe the clinical and histological features, predisposing factors, treatment and survival rate of oral carcinoma cuniculatum.

MATERIAL & METHOD

All patients with histologically confirmed CC of the oral cavity treated between January 2013 and August 2022 in a specialized center were retrospectively included. Patients were identified using the database ADICAP ("Association pour le Développement de l'Informatique en Cytologie et Anatomie Pathologique"). Once identified, the charts were reviewed.

RESULTS

Ten patients were included. CC lesions were mainly located in the mandibular or maxillary gingiva, while the 2 remaining lesions were located in the mobile tongue. The tumor showed local aggressiveness: mandibular or maxillary osteolysis was systematically found for gingival CC, while tongue lesions were classified cT3. Fifteen biopsies were performed in these 10 patients, histological diagnosis is difficult on a limited tissue sample. All patients underwent curative management with oncological excision surgery combined with neck lymph node dissection, and adjuvant radiotherapy (except one patient).

DISCUSSION

The main problem is the difficulty of diagnosis when biopsies are performed, which leads to a significant delay in diagnosis compared with SCC. In the event of clinico-histological discordance after biopsy, CC should be considered.

Oral Carcinoma Cuniculatum: A Variant of Squamous cell Carcinoma with Unique Histological Characteristics and a Diagnostic Challenge

Oral carcinoma cuniculatum (OCC) is a rare squamous cell carcinoma (SCC) variant with low incidence often due to misdiagnosis. This report aims to highlight this unique variant of SCC which is suggested to have a better prognosis with a focus on its histopathological features in comparison with similar clinical entities.

Carcinoma Cuniculatum: A Rare Malignancy With Unique Diagnostic Dilemmas

Carcinoma cuniculatum is an extremely rare and often indolent cancer that can mimic a benign process, such as osteomyelitis or odontogenic infections. This results in a definitive diagnosis that is delayed. To complicate the evaluation of this uncommon neoplasm, biopsies are often misinterpreted secondary to an incorrectly obtained tissue sample. Incisional biopsy needs to be done in a specific manner with a high degree of clinical suspicion incorporated into the patient assessment for the most accurate diagnosis. Local and distant failure rates are low with aggressive surgical resection and surgery upfront remains the treatment of choice when feasible. We present two cases that highlight the difficulty in accurate diagnosis and management of these rare cancers.

Carcinoma Cuniculatum of the Maxilla Arising From Oroantral Fistula: A Report of an Extremely Rare Case

Carcinoma cuniculatum (CC) is extremely rare in the maxilla. Here, we report a case of CC arising from an oroantral fistula (OAF). The patient was a 70-year-old Japanese man who was followed up for a non-closing OAF. Although there were no findings based on an intraoral examination, follow-up contrast-enhanced computed tomography and magnetic resonance imaging showed a 22-mm mass in the maxilla close to the OAF. Histologically, cystic and endophytic papillary proliferation of squamous epithelium with abundant keratinization mimicking rabbit burrows occupied the alveolar bone. This tumor was directly connected to the atypical proliferation of the covering epithelium of the OAF. The tumor cells showed mild cytological atypia and a few mitoses. Finally, the patient was diagnosed with CC arising from an OAF. CC is often misdiagnosed; nonetheless, the unique endophytic, branching, and tunnel-like structure is a hallmark of this tumor. We present the first well-documented case of CC arising from an OAF, discuss its diagnostic features, and highlight its differences from other common benign and malignant pathological entities.

Cuneiform (cuniculatum) variant of oral squamous cell carcinoma revisited: Presentation of two cases and literature review of a rare entity

BACKGROUND

Oral carcinoma cuniculatum (OCC) is a rare, locally aggressive tumor, which tends to invade underlying bone. We present two cases of OCC, one demonstrating invasion of the mandible and the other limited to the tongue.

METHODS

An 87-year-old male presented with a right-sided buccogingival lesion. Biopsy results led to a diagnosis of verrucous hyperplasia, which was later revised to OCC. Additionally, a 94-year-old female presented with a left lateral tongue lesion. A biopsy showed in-situ and invasive keratinizing squamous cell carcinoma that was later defined as a soft tissue OCC.

RESULTS

Following surgical resection, the diagnosis of OCC was established in both patients. We provide a comprehensive literature review of OCC in the context of both case presentations.

CONCLUSIONS

OCC is a rare entity, which has a tendency to be misdiagnosed. We emphasize the importance of recognizing the common features of OCC in order to aid in accurate diagnosis.

Oral carcinoma cuniculatum: an unacquainted entity with diagnostic challenges-a case report

BACKGROUND

Oral carcinoma cuniculatum (OCC) is an unacquainted well-differentiated subtype of oral squamous cell carcinoma, which displays unique clinic-pathological features. Up to date, OCC remains rare with about 75 reported cases, and is frequently missed or even misdiagnosed.

CASE PRESENTATION

The aim of the present work was: to report a case of OCC in mandibular gingiva and to highlight its main clinic-pathological diagnostic features: with an exophytic cobble-stone surface and a characteristic endophytic burrowing architecture, as well as to differentiate between it and other closely similar lesions including verrucous carcinoma, papillary squamous cell carcinoma, and well-differentiated conventional oral squamous cell carcinoma.

CONCLUSIONS

An accurate diagnosis of OCC entails awareness of the clinicians and pathologists about its entity, proper knowledge of the diagnostic clinical and histopathological evidence, and the ability to differentiate it from closely similar lesions.

Carcinoma Cuniculatum of the Oral Cavity: A Series of 6 Cases and Review of Literature

Carcinoma cuniculatum (CC) is a rare variant of squamous cell carcinoma (SCC) that is characterized by minimal cytologic atypia and a unique deeply infiltrative growth pattern resembling rabbit burrows (cuniculi). With less than 75 cases reported in the head and neck, the clinical and pathologic spectrum of this entity remains poorly understood. A retrospective review of the clinical and pathologic features of archival cases of oral CC was performed. A total of six cases of oral CC were identified. Age ranged from 25-77 years; the male-to-female ratio was 5:1. All patients had a long-standing history of tobacco and betel-quid consumption. The tumors were distributed in the gingivobuccal sulcus (n = 2), the tongue (n = 2), buccal mucosa (n = 1), and the palate (n = 1). Histology in all cases typically revealed a tumor composed of well-differentiated squamous epithelium, devoid of atypia, lining deeply infiltrative, large-sized, branching, keratin-filled cavities, resembling rabbit-burrows. Dense lymphocytic infiltrates and discharging micro-abscesses were regular features. Underlying bone invasion and lymph node metastasis were observed in 1 patient. One patient with a tongue tumor developed locoregional recurrence at 10 months while none developed distant metastasis. Oral CC is a rare and under-recognized variant of SCC with locally aggressive behavior. Lack of familiarity with this variant exacerbated by the absence of cytologic anaplasia makes CC susceptible to multiple negative biopsies and erroneous diagnoses. Awareness of this clinicopathologic entity is essential to allow its accurate diagnosis and optimal management.

Oral carcinoma cuniculatum

Oral Carcinoma cuniculatum(OCC) is rare variant of squamous cell carcinoma. The histopathological features of this type of carcinoma makes it special in the literature of Pathology. The appearance of deep invading epithelial islands with pool of keratin cores very similar to rabbit burrows gives the term cuniculatum to the carcinoma. Here we present a case of OCC on the lateral surface of the tongue. Early diagnosis of such case is very important to distinguish it distinctly from the other entities of squamous cell carcinoma like verrucous carcinoma. The knowledge of existence of such entity of squamous cell carcinoma occurring in the oral cavity is very important to facilitate correct treatment planning and management.

"Migratory Kerato osteomyelitis" - A refractory lesion of the mandible: A pathologist's and surgeon's dilemma!!

A 62 year old female patient presented with a chief complaint of non healing extraction socket in the lower left back teeth region. She underwent extraction of 37 at a private clinic following which an ulceroinfiltrative lesion developed at operated side. Multiple biopsies from the lesion were inconclusive. Computed tomography revealed an osteolytic lesion radiologically simulating carcinoma or a chondrosarcoma. Because of persistent debilitating symptoms the patient underwent Wide local excision (WLE) with left segmental mandibulectomy. Frozen sections were negative for malignancy. All margins were free from malignancy. Lymph nodes dissected showed reactive morphology. Ziehl-Neelsen, Periodic acid-Schiff and Gram stain were all negative. The lesion continued to spread even after successful surgical intervention with adequate surgical margin. The patient was eventually lost because of severe cardiac arrest during her last surgical intervention for mandibular arch reconstruction. As the lesion migrated from one side of the mandible to the other, kept showing clinical features of inflammation of the bone and bone marrow simulating features of osteomyelitis and the continued presence of keratin histologically, we contemplated whether we could give a nomenclature to the lesion as that of "Migratory Kerato osteomyelitis of the oral cavity." This could be one of case of a lifetime where multiple consultations with oral and general pathologists failed to reach a conclusive diagnosis!

Carcinoma Cuniculatum of the Larynx

Carcinoma cuniculatum (CC) is a rare clinicopathologic variant of squamous cell carcinoma. Histologically, it is characterized by invasive growth of bland, acanthotic, and keratinizing squamous epithelium that forms multiple rabbit burrow-like, keratin-filled crypts and sinuses. We present a 51-year-old male smoker with CC of the left vocal cord. The tumor was staged T1a and the patient was disease-free 12 months after surgery. To our knowledge, this is the fourth case of CC of the larynx reported in the English literature and the first, due to its early diagnosis, where radical surgery was not performed. We highlight the necessity for awareness of this entity and coordination between otolaryngologists, radiologists, and pathologists for early diagnosis and organ-sparing surgical treatment.

Carcinoma Cuniculatum of Mandible Masquerading as Odontogenic Keratocyst: Challenges in the Histopathological Diagnosis

Carcinoma cuniculatum is a locally aggressive, low-grade variant of squamous cell carcinoma. Though primarily a tumour of the skin, it has also been found to be arising from various mucosal surfaces including oral mucosa. When it occurs in the mandible it starts as a mucosal lesion which progressively invades the jaw and destroys the underlying bone, often presenting as a cystic lesion. With only around 30 cases reported in the mandible, this entity remains an elusive one for the pathologist and all except a few cases reported so far, had been misdiagnosed initially. The delay in the diagnosis is a major concern as it results in further progression of the disease with extensive involvement of bone and associated soft tissue structures. The aim of this article is to discuss the histopathological challenges faced in arriving at the diagnosis of a case of carcinoma cuniculatum involving the mandible. Owing to its overlapping clinico-pathological characteristics with odontogenic keratocyst the lesion has been misdiagnosed initially resulting in inadequate management, leading to multiple recurrences and unexpected complications. As a few cases like the present one had been erroneously diagnosed as odontogenic keratocyst previously, it becomes important to identify the varied clinical presentation and unique histopathological characteristic of carcinoma cuniculatum of mandible to help us in recognizing this often-missed entity at an earlier stage, so that it can be managed effectively.

Cystic Squamous Cell Carcinomas of the Jaws: Twelve Cases Highlighting Histopathological Pitfalls

Cystic squamous cell carcinomas (SCCs) of the jaws, including carcinoma cuniculatum, are rare, slow growing, and relentlessly invasive. The aim of this article is to present 12 cases, 4 of which were designated as carcinoma cuniculatum on the basis of deeply endophytic, anastomosing channels of cystic stratified squamous epithelium and keratin microabscesses. The other 8 were also cystic, but more heterogeneous morphologically and were diagnosed as well differentiated SCCs. Six patients were female, 6 were male (mean age = 74.0 years, range = 50-94 years). Six tumors affected the mandible, 6 the maxillary alveolus with or without extension into the hard palate. All patients underwent primary resection with neck dissection and were staged as T4a N0 M0. In 4 patients, diagnosis was delayed as a result of superficial biopsies and/or confusing histopathology. Cystic SCCs of the jaws can be difficult to diagnose and clinicoradiological correlation is essential. Long-term follow-up is mandatory.

Esophageal carcinoma cuniculatum: systematic review of the literature and report of two cases

BACKGROUND AND AIMS

Carcinoma cuniculatum (CC) is a rare variant of an extremely well-differentiated squamous cell carcinoma. The most commonly involved site is the skin, with a preference for the sole. Only 15 cases of esophageal CC have been reported so far. Based on published data, the clinical behavior of CC has not been clearly defined. We describe the clinical-pathologic features of two cases of esophageal CC, and provide a review of the available literature, to shed more light on this unusual tumor.

METHODS

A detailed gross and histologic analysis was performed on two cases of surgically treated esophageal CC. The patients were followed-up after surgery. A systematic search was also done concerning studies focused on esophageal CC. A search of the electronic databases MEDLINE-PubMed was conducted using the following research terms: (esophagus) AND (cuniculatum carcinoma).

RESULTS

Both patients were alive at last follow-up at six and nine months from surgery without any recurrence. Concerning the fifteen cases reported from the systematic review, median follow-up after surgery was very long as compared to common esophageal cancers (4.0 years), with only one recurrence observed.

CONCLUSION

CC shows an indolent clinical behavior, with a low recurrence rate after radical surgery. The diagnosis of this rare tumor is typically made after surgery. An aggressive approach is required with curative intents.

[Carcinoma cuniculatum: An unusual oral tumor]

We report on a case of carcinoma cuniculatum (CC) of the maxillary gingival mucosa. A 60-year-old woman presented with an exophytic gingivo-palatal mass with slow growth and osteolytic evolution. A first performed biopsy was negative for malignancy. The diagnosis of CC was established on the surgical representative biopsy. CC is a rare low-grade variant of squamous cell carcinoma that is usually found in the foot or in oral cavity. The pathognomonic microscopic feature of CC is an endo- and/or exophytic lesion composed by a well differentiated squamous epithelium infiltrating into underlying stroma forming a complex pattern of keratin cores and keratin filled "rabbit warren" crypts. CC is a locally evolutive carcinoma with a usually good prognosis usually without lymph node or distant metastatic evolution.

Oral carcinoma cuniculatum, an unacquainted variant of oral squamous cell carcinoma: A systematic review

Purpose

Oral carcinoma cuniculatum is a rare well-differentiated variant of oral squamous cell carcinoma. The purpose was to systematically review its unique features to differentiate it from other variants as verrucous carcinoma, papillary squamous cell carcinoma and well-differentiated squamous cell carcinoma.

Materials and Methods

A systematic review was performed using MEDLINE, Dentistry and Oral Sciences Source and PubMed databases and any existing articles related to the research subject missed in the search strategy to screen ones reporting cases occurring exclusively in the oral cavity in English literature. Variables analyzed included clinical, etiologic, imaging, histopatholgical features, treatment, follow-up and survival rates.

Results

From 229 hits, 17 articles with 43 cases were included in the systematic review. Clinically it showed a female predilection with pain and/or ulceration of a relatively long duration and exudation being the most common symptoms. Histologically, it showed more endophytic features comprising well-differentiated squamous epithelium with absent or minimal cytological atypia and multiple keratin filled crypts or cuniculus. Inflammatory stromal reaction and discharging abscesses were reported in most of the cases. Bone destruction was predominant in most imaging features. Complete surgical resection with a safety margin was the treatment of choice in most of the cases with few recorded recurrence cases.

Conclusion

Apprehensive knowledge of oral carcinoma cuniculatum unique features is essential to avoid its misdiagnosis and provide proper treatment especially for recurrent cases.

Oral carcinoma cuniculatum presenting with moth-eaten destruction of the mandible

OBJECTIVE

Carcinoma cuniculatum (CC) is a rare variant of squamous cell carcinoma. We describe the clinicopathologic findings in a new case.

STUDY DESIGN

This is a literature review and retrospective study of a case with CC.

RESULTS

The clinical and imaging findings of CC are diverse; some cases might be challenging to diagnose accurately by biopsy. This article reports a case of CC that occurred in the retromolar region with involvement of the mandible. The patient was a 39-year-old man. Clinically, the lesion manifested as an ulcerative mass in the mandibular molar region. Imaging results showed that the lesion in the jaw exhibited moth-eaten destruction without obvious expansion of the jaw bone. The postoperative pathologic examinations were consistent with CC; additionally, metastases were present in 1 level II lymph node and 1 submandibular lymph node. Left soft tissue metastasis and right cervical lymph node metastases were detected 10 and 27 months after surgery, respectively.

CONCLUSIONS

CC is a rare epithelial malignant tumor and has variable clinical manifestations. The diagnosis of CC mainly depends on pathologic features. Most patients with CC have a good prognosis; only a small percentage of patients might experience lymph node metastasis.

Proliferative endophytic lesion of the maxilla: A diagnostic challenge

Carcinoma cuniculatum (CC) is an extremely rare neoplasm of the oral cavity. It is essentially a well-differentiated variety of squamous cell carcinoma and shows lower metastasis risk. The histological features of CC can mimic that of papillary squamous cell carcinoma or verrucous carcinoma. CC commonly affects the plantar region of the foot, and very few cases have been described in the oral cavity. The classical histological characteristics noted are infiltration of underlying connective tissue by squamous epithelium with keratin cores and keratin-filled crypts. Herewith, we present a case of CC of the right maxilla in a young Dravidian male patient who works in a battery factory. The case presented a diagnostic challenge both clinically and histopathologically before it was completely resected using a total maxillectomy technique. The case delineates the diagnostic challenge and management of the disease.

The Spectrum of Oral Lesions Presenting Clinically With Papillary-Verrucous Features

PURPOSE

We sought to study the spectrum of oral pathologies presenting clinically with papillary-verrucous features.

MATERIALS AND METHODS

A 10-year (2007 to 2016) retrospective study of oral papillary lesions was undertaken. All biopsy reports that included a clinical description of papillary or verrucous architecture were retrieved. The data collected included clinical features, size, color, location, histopathologic diagnosis, age, and gender.

RESULTS

The study included 137 patients, with a total of 150 lesions. The ages ranged from 10 weeks to 84 years (mean, 49 years). Histopathologically, 60% of cases were human papillomavirus (HPV) related, 19% showed hyperplasia, 11% had hyperplastic candidiasis, 7% were dysplastic or malignant, and 3% were benign of unknown etiology. Among the 7% of lesions diagnosed with dysplasia or malignancy, only 60% were suspected to have malignancy at the time of biopsy. HPV-related lesions and hyperplasia were most frequently found on the tongue (38% and 41%, respectively) and soft palate (21% and 14%, respectively). Hyperplastic candidiasis was most frequently found on the buccal mucosa and tongue (35% and 24%, respectively). Squamous cell carcinoma was found in 1.3% of total lesions and verrucous carcinoma in 1.3%. Of the verrucous or papillary malignant lesions, 50% were found on the gingiva. Most malignant lesions occurred in the 40- to 60-year age group.

CONCLUSIONS

The results of this study suggest that, because of the wide spectrum of entities presenting clinically with a papillary-verrucous architecture, biopsy is necessary for diagnosis. The clinical presentation allowed for overall accurate diagnosis in only 47% of cases and 60% accuracy in dysplastic or malignant cases. It is of considerable importance to correctly identify those lesions that are HPV related but at the same time to rule out those lesions that are unrelated to HPV to help alleviate a patient's anxiety. Most important, biopsy is mandatory for the recognition of malignant lesions with a papillary-verrucous architecture, which may mimic other benign entities in the group of papillary-verrucous lesions.

Verrucous Carcinoma of the Foot - Report of Two Cases

Verrucous carcinoma (VC) is a rare variant of a well-differentiated squamous cell carcinoma (SCC) with a low grade of malignancy. Epithelioma cuniculatum (EC) is a subtype of VC, usually found on the sole of the foot.

Two patients, a 55-year-old female, and a 77-year-old male, with VC were treated at the Clinic of Dermatology and Venereology, Clinical Center of Serbia, from 2002 to 2011. Both patients presented with a tumor on the foot. Incisional biopsies showed a well differentiated squamous cell carcinoma. Foot x-rays showed bone involvement in one case. One patient underwent surgical amputation of the lower extremity, while the other had a partial amputation of the affected foot.

In the initial stage of the disease, it is difficult to distinguish pseudoepitheliomatous hyperplasia from verrucous carcinoma. The superficial biopsy of EC lesion may mislead to a histopathological diagnosis of warts or condylomas. Multiple deep biopsies are necessary for accurate and timely diagnosis of verrucous carcinoma.

Update from the 4th Edition of the World Health Organization of Head and Neck Tumours: Tumours of the Oral Cavity and Mobile Tongue

There have been several additions and deletions in Chapter 4 on Tumours of the oral cavity and mobile tongue in the 2017 fourth edition of the World Health Organization Classification of Tumours of the Head and Neck. This chapter excludes the oropharynx, which now is a stand-alone chapter acknowledging the uniqueness of the oropharynx from the oral cavity. New entries in Chapter 4 include rhabdomyoma, haemangioma, schwannoma, neurofibroma and myofibroblastic sarcoma in the section titled Soft tissue and neural tumours. Discussion of salivary gland entities have been reduced and includes mucoepidermoid carcinoma and pleomorphic adenoma as the other salivary gland types are discussed elsewhere. In the Haematolymphoid tumours section, like the salivary gland section, only tumors that commonly present in the oral cavity are discussed in Chapter 4. Excluded entities in the updated classification include papillary hyperplasia, median rhomboid glossitis, keratoacanthoma, focal oral mucinosis, and secondary tumors. This article will summarize the changes in the new classification since the 2005 edition focusing on selected entities that have had significant changes along with new entries.

Oral Carcinoma Cuniculatum: A New Entity in the Clinicopathological Spectrum of Oral Squamous Cell Carcinoma

Carcinoma cuniculatum is principally recognized as a variant of carcinoma involving foot. The World Health Organization (WHO) recognizes Oral Carcinoma Cuniculatum (OCC) as a distinct and rare clinicopathological variant of Oral Squamous Cell Carcinoma (OSCC). OCC is confused clinically and histologically with Verrucous Carcinoma (VC) and is often misdiagnosed as either VC or OSCC. To best of our knowledge, till date, only 50 cases of this tumour have been reported in oral cavity (including the present case) and only limited number of cases have been reported from Indian subcontinent. Pathognomonic feature of OCC is proliferation of stratified squamous epithelium and its infiltration into underlying stroma forming a complex pattern of keratin cores and keratin filled crypts. These complex crypts give it a likeness of rabbit burrow hence, the name cuniculatum (cuniculatus='rabbit warren'). The report aims to present a case of OCC of mandibular gingiva, discuss its diagnostic features and highlight its differences from VC and OSCC.

Extensive carcinoma cuniculatum of the mandible

Carcinoma cuniculatum (CC) is a rare variant of squamous cell carcinoma first described in 1954. Cases of CC in the head and neck are exceedingly rare, with 66 cases reported since 1977. These tumors are generally low-grade, well-differentiated and locally aggressive malignancies. Patients are often subjected to a long period of misdiagnoses given the clinical similarity of these entities to odontogenic cysts and abscesses. We report a case of a carcinoma cuniculatum of the mandible with very advanced local involvement of disease, highlighting the unusual characteristics of this rare tumor that are important for clinicians to recognize. Clinical presentation, histology, risk factors, treatment options, and prognosis are also reviewed.

A Rare Case of Carcinoma Cuniculatum Involving the Larynx in Association with a Saccular Cyst

Carcinoma cuniculatum (CC), a rare, well-differentiated variant of squamous cell carcinoma, is uncommon in head and neck sites but when it does occur is most common in the oral cavity. Here we report a rare case of CC involving the larynx. A 49-year-old man presented with 10 months of worsening hoarseness and, despite multiple biopsies, no diagnosis of malignancy could be established. Eventual partial excision of the lesion and histologic review of prior specimens confirmed the diagnosis of CC. Focally, a transition to respiratory epithelium indicated the presence of an associated saccular cyst. Total laryngectomy was performed and 6 months later the patient is free of disease. Only two prior cases of CC have been reported in the larynx. Diagnosis of CC is challenging given the low grade histologic features and awareness of this entity for both treating physicians and the pathologist is important to reach a diagnosis of malignancy. This case highlights the challenges in diagnosis of CC, especially in unusual locations and when associated with other lesions such as a saccular cyst. Awareness of this rare tumor type combined with close communication between treating clinicians, radiologists and pathologists should allow earlier diagnosis and treatment.

Oral carcinoma cuniculatum: two cases illustrative of a diagnostic challenge

Carcinoma cuniculatum is a rare variant of squamous cell carcinoma originally described on the sole of the foot and for a long time believed to be restricted to the skin. However, since its first description in 1954, several cases have been reported at other sites. Carcinoma cuniculatum characteristically invades the underlying subcutaneous, submucosal, or bone tissues, forming so-called "rabbit burrows," with crypts filled with keratin that are of utmost importance for distinguishing this neoplasm from other variants of squamous cell carcinoma. Oral carcinoma cuniculatum is an even rarer entity that is frequently misdiagnosed initially, a phenomenon described in about one-third of previously reported cases. The aim of this report is: (1) to describe the clinicopathologic features of 2 new cases of oral carcinoma cuniculatum, initially misdiagnosed as infected orthokeratinized cyst and abscess, respectively; and (2) to review the related English language literature.

Carcinoma cuniculatum of the esophagus and tongue: report of two cases, including TP53 mutational analysis

Carcinoma cuniculatum (CC) is a rare variant of extremely well differentiated squamous cell carcinoma. We present the clinicopathological features of two cases of CC; one lingual and one esophageal case with a molecular genetic study regarding the TP53 gene mutational status. Case 1 was a 62 year old male with enlarging chronic ulcer in the tongue. Case 2 was a 77 year old male with progressive dysphagia and odynophagia. Both patients were treated surgically. Both tumors showed deeply invaginating, keratin-filled, burrowing crypts lined by very well differentiated squamous epithelium. The esophageal tumor showed varying degrees of reactive nuclear atypia largely limited to the areas with dense intratumoral infiltration of neutrophils. No mutation of TP53 was identified in the esophageal case. Cytologic atypia limited to areas of significant acute inflammation may occur in CC and should, in the absence of aggressive stromal invasion, not preclude a diagnosis of CC.