CD56 expression in basaloid anal squamous cell carcinoma - A potential diagnostic pitfall.

Anal squamous cell carcinoma (SqCC) is a morphologically heterogeneous entity. Basaloid and non-keratinizing anal SqCC may be confused with other tumors including neuroendocrine carcinoma due to morphologic overlap, and expression of neuroendocrine markers is not well-studied in anal SqCC. Prompted by a case of anal SqCC that was initially misdiagnosed as neuroendocrine carcinoma on the basis of morphology and CD56 expression, we retrospectively examined the expression of neuroendocrine markers CD56, synaptophysin, and chromogranin in 48 cases of basaloid anal SqCC, with clinicopathologic correlation. HPV16 was identified in 46 cases, HPV33 in one case, and one case was HPV-negative. Three (6.3%) cases demonstrated CD56 expression, including two with diffuse and one with focal expression. Two CD56-positive cases demonstrated basaloid morphology with peripheral palisading and the other demonstrated adenoid cystic/cylindroma-like morphology. None of the cases showed significant synaptophysin or chromogranin expression. The three cases expressing CD56 were HPV16-positive, and one demonstrated a CTNNB1 mutation. There was no difference in clinicopathologic features including stage, outcome, or HPV status, between CD56-positive and negative groups. Our findings support that CD56 expression is infrequently expressed in anal SqCC and is not indicative of neuroendocrine differentiation in the absence of expression of more specific neuroendocrine markers such as synaptophysin and chromogranin. Pathologists should be aware that CD56 expression may occur in basaloid anal SqCC and is a diagnostic pitfall due to morphologic overlap with neuroendocrine carcinoma and other tumors including basal cell carcinoma.

Corneal Toxicity Associated With Aquarium Coral Palytoxin.

PURPOSE: To report a series of patients who developed corneal toxicity after exposure to aquarium coral palytoxin. DESIGN: Multicenter retrospective case series. METHODS: Retrospective review. RESULTS: Seven patients presented with corneal findings ranging from superficial punctate epitheliopathy to bilateral corneal melt with subsequent perforation. Among those with mild corneal findings, resolution was achieved with topical steroids and lubrication, whereas some patients who developed progressive corneal melt required therapeutic penetrating keratoplasty. The history in all patients revealed exposure to aquarium zoanthid corals shortly before disease onset. A review of the literature revealed that there are few prior reports of coral-associated corneal toxicity and that some species of coral secrete a substance known as palytoxin, a potent vasoconstrictor that inhibits the membranous sodium-potassium ATPase pump across cell types and can cause rapid death if inhaled or ingested. CONCLUSIONS: This is the largest case series to date demonstrating patients with aquarium coral palytoxin-associated corneal toxicity, and is the first to provide details of related histopathologic findings. Similar to other forms of toxic keratoconjunctivitis, a detailed history and careful clinical assessment are required, as well as timely removal of the offending agent from the patients' ocular milieu and environment. Mild ocular surface and corneal disease may be treated effectively with aggressive topical steroid therapy and lubrication. Given the potential severity of ocular as well as systemic adverse effects, there should be increased awareness of this entity among eye care professionals, aquarium enthusiasts, and the general public.