The Reactivity of Hydroxyl Radicals toward Boric Acid as a Function of pH.

Boric acid and its counter-base, borate, are a commonly used buffer pair in many systems where hydroxyl radicals are generated. Boric acid is also used in light water-cooled nuclear reactors to control the excess reactivity of the nuclear fuel. Hydroxyl radicals are generated within the cooling water of the reactor because of intense radiation.

Clear cell adult rhabdomyoma-a rare variant of an unusual tumour.

Adult rhabdomyoma is an uncommon benign mesenchymal neoplasm that most often occurs in the head and neck. We present a 70 year-old male with a swelling on the floor of the mouth. Subsequent excision of the tumor revealed a hitherto undescribed morphological variant of this tumor that features a predominance of clear cells, which on light microscopy may mimic other other clear cell tumours of the head and neck region.

Ocular Crystal-Storing Histiocytosis with Co-existing MALT Lymphoma-A Rare Case with Cytologic and Heretofore Not Reported Findings on Frozen Section.

Background: Crystal-storing histiocytosis (CSH) is a rare disorder which most commonly occurs in the setting of concurrent lymphoproliferative disease. Morphologically, it consists of aggregates of histiocytes containing eosinophilic crystalline material, which in most cases is composed of aggregated abnormal light chains.

Methods: Using histomorphology, immunohistochemistry and in situ hybridization, the authors characterize a rare case of orbital CSH associated with extranodal marginal zone (MALT) lymphoma and report for the first time the frozen section features of CSH.

The Challenge of "Monomorphic" Mucoepidermoid Carcinoma-Report of a Rare Case with Pure Spindle-Clear Cell Morphology.

Background: Mucoepidermoid carcinoma is a malignant salivary gland tumor which, in most cases, is composed of variable proportions of mucous, epidermoid, and intermediate cells.

Methods: We report a case of parapharyngeal mucoepidermoid carcinoma with highly unusual ("monomorphic") light microscopic features as well as atypical immunohistochemical properties. Molecular analysis was performed using the TruSight RNA fusion panel.

Oncocytic low-grade myoepithelial carcinoma ex pleomorphic adenoma - A rare case illustrating key learning points.

Background: Oncocytic myoepithelial carcinoma ex pleomorphic adenoma neoplastic is a rare neoplastic event and may not display overt malignant radiological features.

Methods: Using routine histopathology and immunohistochemistry, we characterize a case of low-grade oncocytic carcinoma ex pleomorphic adenoma.

Results: The tumor arose in the left parotid gland in a 59 year old female.

Sclerosing polycystic adenoma - A review.

This review summarizes the current state of knowledge on sclerosing polycystic adenoma, including epidemiological/clinical, histopathological/cytopathological, ultrastructural, immunohistochemical and etiopathogenetic/molecular genetic aspects. Differential diagnostic issues are briefly discussed.

Sclerosing microcystic adenocarcinoma of the parotid gland - The first recorded case with histo-cytopathologic correlation and a brief review of the literature.

We present a case of a 1.0 cm primary tumor of the left parotid gland that meets the histological criteria for the recently described entity sclerosing microcystic adenocarcinoma. The patient was a 73-year-old man with a concurrent tonsillar squamous cell carcinoma, and a history of nasopharyngeal carcinoma treated with radiotherapy 23 years prior.

Epithelioid Sarcoma of the External Auditory Canal: An Uncommon Tumor at an Unusual Site and a Brief Overview of the Literature.

We present a case (41 years old pregnant female) with epithelioid sarcoma arising in the left external auditory canal. On immunohistochemistry, the tumor cell diffusely expressed cytokeratins and showed patchy expression of ERG and CD34. The neoplastic cells demonstrated uniform loss of INI1-expression.

Adenoid cystic carcinoma with dedifferentiation/expansion of the luminal cell component and preserved biphasic morphology - Early high-grade transformation.

We present two patients (29 and 67 years) with histomorphologic and immunohistochemical evidence of early high-grade transformation of adenoid cystic carcinoma in the nasal cavity and floor of mouth, respectively. The component of early high-grade transformation was characterized by 1) selective expansion of the luminal (CK7+, c-kit+, p63-) cell component with severe cytologic atypia and significantly increased Ki-67 proliferation index, and 2) retained albeit attenuated abluminal (CK7-, c-kit-, p63+) cells, surrounding nests of high-grade luminal cells.

Ectopic Cervical Thyroid Tissue Affected by Fibrosing Hashimoto's Thyroiditis Mimicking Multifocal Metastatic Papillary Thyroid Carcinoma-A Hard Lesson Learnt from an Unusual Case.

We describe a case of ectopic cervical thyroid tissue which was involved by fibrosing Hashimoto's thyroiditis and which mimicked metastatic papillary thyroid carcinoma both on fine needle aspiration cytology and biopsy. The patient underwent total thyroidectomy which revealed fibrosing Hashimoto's thyroiditis, but no carcinoma. The entire thyroidectomy specimen was submitted for histopathological assessment.

Typical and atypical carcinoid tumors of the lung: a clinicopathological correlation of 783 cases with emphasis on histological features.

We present 783 surgical resections of typical and atypical carcinoid tumors of the lung identified in the pathology files of 20 different pathology departments. All cases were critically reviewed for clinical and pathological features and further correlated with clinical outcomes. Long-term follow-up was obtained in all the patients and statistically analyzed to determine significance of the different parameters evaluated.

Preservation of the superficial temporal artery during resection of a pseudoaneurysm: A case report and review of the literature.

The superficial temporal artery (STA) is a structure that is particularly vulnerable to injury, given its prominent location in the head and neck region. Pseudoaneurysms of this artery may be encountered during the management of maxillofacial trauma. This article presents a review of the relevant literature on this topic.

Nasal Cavity Metastasis From Colorectal Cancer Represents End-Stage Disease and Should Be Palliated.

Nasal metastases from colorectal cancer is rare. The presentation of nasal metastases is often very similar to primary nasal sinus adenocarcinoma. A high index of suspicion is required, especially in patients who have had a previous history of colorectal carcinoma.

Lipomatous basal cell adenoma (Basal cell lipoadenoma) - Report of the first two cases.

We present, to the best of our knowledge, the first two cases (60 year old female and 71 year old male) of basal cell adenoma with significant adipocytic components and suggest the term "lipomatous basal cell adenoma" for these lesions. Both tumors presented as slow growing nodules in the parotid gland. The two cases represent different points on a histopathological spectrum with one case being extremely well differentiated with distinct spiradenoma-like histological features; distinct bilayering, duct formation with secretory material and very low proliferative activity and the other case displaying more primitive cytological features composed of a predominant uniform, (p63-positive; CK 7-negative) basaloid, abluminal cell type, high proliferative activity and only scattered true ducts composed of (CK7-positive, p63-negative) luminal cells.

Cervical Myxoid Solitary Fibrous Tumor: Report of an Unusual Variant and a Brief Overview of the Literature.

We present a 49 year old female with a diagnostically challenging myxoid solitary fibrous tumor arising in the soft tissue of the neck. The tumor was diffusely positive for CD34 and STAT6 on immunohistochemistry.

Frequent overexpression of klotho in fusion-negative phosphaturic mesenchymal tumors with tumorigenic implications.

Phosphaturic mesenchymal tumors (PMT) are tumors that cause hypophosphatemia/osteomalacia chiefly by secreting FGF23. We have identified FN1-FGFR1/FGF1 fusion genes in nearly half of PMT, suggesting a central role of FGFR1 pathways in the pathogenesis of PMT. Tumorigenic drivers are unknown for tumors where previous study detected neither fusion, including many in bone, where FISH failed because of tissue decalcification.

Macrocystic (Mammary Analogue) Secretory Carcinoma: An Unusual Variant and a Pitfall in the Differential Diagnosis of Cystic Lesions in the Head and Neck.

Mammary analogue secretory carcinoma (MASC) is a relatively recently described salivary gland adenocarcinoma characterized by ETV6-NTRK3 gene fusion and in most cases indolent clinical behavior. The majority of tumors show an admixture of microcystic, solid, and tubular growth patterns but only a few cases with dominant macrocystic growth have been reported. We report 15 cases of macrocystic MASC.

SOX11 expression in a case of papillary thyroid carcinoma with fibromatosis/fasciitis-like stroma containing BRAF c.1799_1801delTGA and CTNNB1 c.133T>C mutations.

We describe a case of papillary thyroid carcinoma with fibromatosis/fasciitis-like stroma (PTC-FLS) that contained the rare BRAF c.1799_1801delTGA (p.V600_K601delinsE) mutation, which has not previously been reported in this tumour, as well as the CTNNB1 c.

(Mammary Analogue) Secretory Carcinoma of the Nasal Cavity: Report of a Rare Case with p63 and DOG1 Expression and Uncommon Exon 4-Exon 14 ETV6-NTRK3 Fusion Diagnosed with Next Generation Sequencing.

We present a 72 years old male with a left nasal cavity (mammary analogue) secretory carcinoma (SC) which exhibited classical morphological features on light microscopical examination, diffuse strong S100 and mammoglobin positivity on immunohistochemistry, and ETV6-NTRK3 gene fusion on next generation sequencing (NGS) analysis. Unusual features of this tumor are expression of p63 and DOG1 on immunohistochemistry and the atypical junction between Exon 4 of the ETV6 gene and Exon 14 of the NTRK3 gene.

Amyloid and hyaline globules in undifferentiated nasopharyngeal carcinoma.

We characterize the clinicopathological features of two patients (one 38 year old woman and one 42 year old man, both of Chinese ethnicity) with Epstein Barr Virus positive non-keratinizing nasopharyngeal carcinoma from an endemic region with prominent presence of amyloid and one case with both amyloid and abundant intracytoplasmic hyaline globules. The amyloid material was positive for Congo red and showed apple green birefringence when examined under polarized light. The amyloid was immunoreactive for cytokeratins and was located both intra- and extracellularly.