Carcinoma Cuniculatum of the Alveolar Mucosa: A Rare Variant of Squamous Cell Carcinoma Abstract Carcinoma cuniculatum is one of the variants of squamous cell carcinoma. It is significantly rare with an incidence rate < 1% compared to other histological variants of squamous cell carcinoma. Various etiologic factors implicated are trauma, HPV, chronic inflammation and alcohol consumption but real causative agent still remains unclear. Initially it resembles plantar wart which slowly progress to bulky exophytic mass in the sole of the foot, where cases have been reported first. In the oral cavity it presents clinically as an exophytic growth and slowly invades the jaw and destroys the underlying bone. Microscopically it exhibits as both exophytic and endophytic epithelial masses along with well differentiated and pronounced hyperkeratosis. Treatment includes surgical resection alone unlike other variants which are treated by radiation with or without chemotherapy. Here we present a case of carcinoma cuniculatum occurred in alveolar mucosa of a 47 years old female. It presented as an exophytic growth in mandibular alveolar region, with histological features consistent with carcinoma cuniculatum.

Non-calcifying Langerhans Cell-Rich Variant of Calcifying Epithelial Odontogenic Tumor: A Distinct Entity with Predilection for Anterior Maxilla Abstract Calcifying epithelial odontogenic tumor (CEOT) is an uncommon locally invasive epithelial odontogenic tumor of the jaws associated with amyloid production. Intraosseous presentations are most common and they frequently occur in the posterior mandible. A non-calcifying Langerhans cell-rich variant of CEOT (NCLC CEOT) has been described with predilection for the anterior maxilla. Interestingly, all reported cases of NCLC CEOT have occurred in Asian population. We present a case of a 43-year old Caucasian female with a large radiolucent lesion involving the left anterior maxilla with histologic features of NCLC CEOT. This is the first reported case of this rare variant of CEOT in a Caucasian individual.

Histiocytic Necrotizing Lymphadenitis Involving the Neck: Radiology-Pathology Correlation Abstract Histiocytic necrotizing lymphadenitis is an uncommon autoimmune condition characterized by fever, leukopenia, and neck swelling. Diagnostic imaging, including ultrasound and CT, typically demonstrates conglomerates of enlarged cervical lymph nodes with hypervascular cortices and areas of necrosis. Ultimately, the diagnosis is confirmed with the histopathologic findings of paracortical coagulative necrosis with karyorrhectic debris, abundant histiocytes, and absence of neutrophils. Other potential etiologies, such as other causes of infectious lymphadenitis, tuberculosis, lymphoma, and systemic lupus erythematosus, must be excluded. These features are exemplified in this sine qua non radiology–pathology correlation article.

Null Cell Adenoma of the Pituitary: Pseudo-rosettes Say It Best When Immunohistochemistry Says Nothing At All! Abstract Null cell adenoma is composed of adenohypophyseal cells that show no evidence of any specific cell type differentiation by immunohistochemistry or transcription factors like pituitary-specific positive transcription factor 1 and steroidogenic factor 1. Though rare, pituitary ependymoma and germinoma are also known to occur at sellar region and in such instances, it is challenging to differentiate them from a pituitary null cell adenoma featuring papillary architecture and perivascular pseudo-rosettes. We describe a case of an elderly diabetic lady presenting with headache and blurring of vision for past 3 months due to a sellar tumour. The histology was diagnostically challenging with notable presence of numerous perivascular pseudo-rosettes and negative immunoreactivity for all pituitary hormones. The differential diagnosis and importance of ancillary techniques is discussed.

Heterotopic Gastrointestinal Cyst of the Oral Cavity Radiology–Pathology Correlation Abstract Heterotopic gastrointestinal cyst of the oral cavity is a rare congenital lesion that may arise from ectopic undifferentiated endodermal cells. Imaging, particularly MRI, is useful for surgical planning. On MRI, the cysts typically demonstrate high signal on T2-weighted sequences and variable signal on T1-weighted sequences, which can resemble other conditions, such as dermoids. On histology, the appearance of these lesions can be variable, and may include stratified squamous, simple and ciliated columnar, as well as foveolar and intestinal-type epithelia, often surrounding by smooth muscle. Complete surgical excision is the treatment of choice.

Head and Neck Sinus Histiocytosis with Massive Lymphadenopathy Radiology–Pathology Correlation Abstract Sinus histiocytosis with massive lymphadenopathy, or Rosai-Dorfman disease, is a rare, benign type of non-Langerhans cell histiocytosis. The radiological findings are often nonspecific, potentially mimicking malignancies. The diagnosis is ultimately made based on pathology, in which the lymph nodes are characterized by a dilated subcapsular sinus filled with histiocytes that can exhibit emperipolesis. Immunohistochemically, the histiocytes are variably CD68 positive and reliably negative for CD1a. The features of head and neck sinus histiocytosis with massive lymphadenopathy are exemplified in this radiology-pathology correlation sine qua non article.

Malignant Transformation of a Desmoplastic Ameloblastoma to Squamous Cell Carcinoma: A Case Report Abstract Ameloblastomas are the most common odontogenic tumors, excluding odontomas. Several morphologic variants have been described including follicular, plexiform, acanthomatous, granular cell, basaloid and desmoplastic. Desmoplastic ameloblastoma differs from other conventional ameloblastomas microscopically, clinically, and radiographically. Ameloblastic carcinoma, the malignant counterpart of ameloblastoma is characterized by cytologic features of malignancy combined within the overall histologic features of conventional ameloblastoma. Malignant transformation of ameloblastoma to squamous cell carcinoma is a controversial subject. Here we report a case of a desmoplastic ameloblastoma with malignant transformation to squamous cell carcinoma in a 49 year old African American man. The patient underwent tumor resection and radiation therapy with no evidence of disease recurrence or progression 16 months post operatively. To our knowledge malignant transformation of a desmoplastic ameloblastoma to squamous cell carcinoma has not so far been reported. This observation may lend some support to the argument that desmoplastic ameloblastoma is phenotypically and biologically distinct entity.

Nasopharyngeal Papillary Adenocarcinoma as a Second Head and Neck Malignancy Abstract Nasopharyngeal adenocarcinomas are rare tumours, and include neoplasms arising from the nasopharyngeal surface epithelium as well as those of minor salivary gland origin, each of which is distinct from the other. The former encompasses nasopharyngeal papillary adenocarcinoma (NPAC), also known as low grade NPAC and thyroid-like NPAC, an extremely unusual malignancy bearing histomorphological similarity to papillary thyroid carcinoma, and displaying indolent clinical behaviour. We report the case of a 41-year-old lady who developed NPAC as a second malignancy five-and-a-half years after being diagnosed and treated for a diffuse astrocytoma in the frontal lobe. In addition, we discuss the differential diagnosis, as well as raise certain pathogenetic considerations with regard to this unique neoplasm.

Ciliated HPV-Related Carcinoma: A Diagnostic Challenge on Frozen Section Abstract Oropharyngeal squamous cell carcinomas associated with high risk HPV show a wide morphological spectrum, including papillary, adenosquamous, lymphoepithelioma-like and sarcomatoid. We report an interesting case of ciliated HPV-related carcinoma arising from tonsillar tissue in a 55-year-old man which was associated with HPV33. This rare variant has been described in only a handful of cases in the literature, and to our knowledge this is the first case specifically associated with HPV33. The presence of cilia is a potential diagnostic problem as it has been traditionally considered a feature of benignancy, and could pose a particular challenge on frozen section. The diagnostic challenges, differential diagnosis of this tumor and the association with HPV33 are discussed.

Non-cystic Sclerosing Polycystic Adenosis: Diagnosis of a Hitherto Undescribed Pattern Abstract A case of sclerosing polycystic adenosis without cysts is described. The lesion occurred as a painless slow growing superficial right parotid lump in a 47 years old woman. The tumor measured 14 × 10 mm and displayed extreme well circumscription, sclerotic stroma with scattered hyaline nodules, sprinkling of mononuclear inflammatory cells and islands of mature fat. The epithelial component was predominantly composed of tubules lined by low columnar to cuboidal epithelium with bland nuclear features. Only focal incomplete acinar differentiation with few cells containing small eosinophilic granules was present. The stroma contained a significant fibromyxoid component with increased cellularity. There was no recurrence on follow-up at 14 months.