Polymorphous low-grade adenocarcinoma of the nasopharynx: a case report and brief review

Extreme acute radiation-induced toxicity in a patient with polymorphous low-grade adenocarcinoma of the nasopharynx and rare variants in DNA repair genes

BACKGROUND

Polymorphous low-grade adenocarcinoma (PLGA) is an extremely rare finding in the nasopharynx. There are no guidelines for the treatment of PLGA in this localization. Radiotherapy may be administered to treat this malignancy; however, in radiosensitive individuals, it is associated with a risk of severe radiotherapy-induced toxicity.

METHODS

We present a case of a 73-year-old woman with locally advanced polymorphous low-grade adenocarcinoma of the nasopharynx who developed a severe adverse acute reaction to radiotherapy leading to treatment discontinuation. Despite intensive treatment, the patient died 40 days after RT initiation. Whole genome sequencing was performed using DNA from peripheral blood mononuclear cells in the search for variants that could explain such extreme toxicity.

RESULTS

We identified a combination of pathogenic variants that may have contributed to the patient's reaction to radiation therapy, including predisposing variants in XRCC1, XRCC3, and LIG4. We also identified candidate variants, not previously described in this context, which could be associated with radiation toxicity based on plausible mechanisms. We discuss previous reports of this rare tumor from the literature and known contributors to radiation-induced toxicity.

CONCLUSIONS

Genetic causes should be considered in cases of extreme radiosensitivity, especially when is not explained by clinical factors.

Polymorphous low-grade adenocarcinoma with cavernous sinus involvement presenting as third nerve palsy

Purpose

Polymorphous low-grade adenocarcinoma is a tumor of the salivary glands that typically localizes within the oral cavity. We present a case of isolated third cranial nerve palsy as the initial presentation of polymorphous low-grade adenocarcinoma involving the left cavernous sinus in a patient status post glaucoma surgery.

Observations

A 68-year-old woman status post glaucoma drainage device implantation in her left eye presented with an isolated left third nerve palsy ten weeks postoperatively. Differential diagnoses included microvascular ischemic neuropathy, postoperative ptosis, and compressive mass. MRI revealed a left cavernous sinus mass, and subsequent excisional biopsy revealed a diagnosis of polymorphous low-grade adenocarcinoma.

Conclusions

There are few cases reporting polymorphous low-grade adenocarcinoma originating from and extending beyond the nasopharynx. This report emphasizes an unexpected neuro-ophthalmic manifestation of this salivary gland tumor.

Myoepithelial Carcinoma of the Nasopharynx: Report of a Rare Case and a Review of the Literature

Salivary gland carcinomas are very rare in the nasopharynx, with the most frequent histologic types being adenoid cystic carcinoma, mucoepidermoid carcinoma and adenocarcinoma, not otherwise specified. Myoepithelial carcinoma (MECA) is a rare tumor of the salivary glands, and there are only three previously reported cases of nasopharyngeal MECA. The case presented is the fourth reported case of MECA in the nasopharynx. Due to the morphologic heterogeneity of MECA, immunohistochemistry is indispensable in ascertaining the diagnosis. MECA is a locally aggressive tumor, but the long-term prognosis of this tumor in the nasopharynx remains uncertain. In our case the tumor was unresectable and the patient was given chemo-radiotherapy. Despite this, residual tumor was seen on nasoscopy 5 months after initial diagnosis and was documented on a re-biopsy which displayed the same histomorphologic features as the original tumor.

Reticular and myxoid non-keratinizing nasopharyngeal carcinoma: an unusual case mimicking a salivary gland carcinoma

We present a case of non-keratinizing carcinoma of the nasopharynx (NK-NPC) with an unusual histopathological pattern. The neoplastic cells were arranged in anastomosing cords embedded in a stroma which contained a significant component of alcian blue-positive myxoid substance forming a reticular pattern. These histopathological features gave an initial impression of a salivary gland-type carcinoma. On immunohistochemistry the tumor cells were strongly and diffusely positive for cytokeratins (AE1-3 and 5/6) and p63 and there was strong and diffuse nuclear positivity for Epstein-Barr virus-encoded small RNA on in situ hybridization. This case highlights the histomorphological variability of NK-NPC. Awareness of the histological spectrum of NK-NPC is important in clinical practice and this is not always adequately highlighted in currently used standard textbooks of Head and Neck Pathology.

Biphasic low-grade nasopharyngeal papillary adenocarcinoma with a prominent spindle cell component: report of a case localized to the posterior nasal septum

A case (female, 39 years of) of thyroid-like nasopharyngeal low-grade papillary adenocarcinoma with a significant spindle cell component is presented. The tumor was located on the posterior nasal septum. The spindle cells displayed nuclear features very much similar to the epithelial component and the two cell types merged imperceptibly. Immunohistochemically, the neoplastic cells (including the spindle cell component) were strongly and diffusely positive for TTF-1, cytokeratins (AE1-3), cytokeratin 19 and vimentin. C-kit immunohistochemistry showed diffuse mild to moderate membranous positivity with focal areas displaying moderate to strong immunoreactivity. EMA was strongly positive in the epithelial component with membranous and cytoplasmic reactivity whereas the spindle cell component was weakly although diffusely positive. Carcinoembryonic antigen, calcitonin, chromogranin A, S100-protein, thyroglobulin, cdx2 and p63 were negative. The proliferative activity (Mib-1/Ki-67) was low; 3-4%. In the molecular genetic study we found no mutations at position 1799 (exon 15) in the BRAF-gene, (BRAFV600E) or in exons 9 and 11 of the KIT-gene.

Thyroid-like papillary adenocarcinoma of the nasopharynx: a case report in a 19-year-old male

Primary thyroid-like papillary adenocarcinomas of the nasopharynx are rare, with only a limited number of cases reported in the literature. However, it is important that pathologists and clinicians alike recognize this entity, as these neoplasms are amenable to surgical resection and carry an excellent prognosis. In this article, we describe the case of a thyroid-like papillary adenocarcinoma of the nasopharynx in a 19-year-old male, with emphasis on clinical findings, histologic and immunohistochemical characteristics, and prognosis. In addition, we include a review of the literature to highlight what we know to date about this rare entity.