Probes for INS

Adenosquamous carcinoma (ADSC) of the head and neck is an aggressive variant of squamous cell carcinoma (SCC). Certain variants of head and neck SCC are human papillomavirus (HPV)-related and have better prognosis. The relationship of HPV to head and neck ADSC has not been investigated. We searched our files for the term "adenosquamous" and head and neck subsites and found cases from 1998 to 2009. The requisite histologic criteria were the presence of SCC combined with distinct gland formation and/or intracellular mucin. DNA in situ hybridization for high-risk HPV, RNA in situ hybridization for high risk HPV E6 and E7 transcripts, and immunohistochemistry for p16 and p53 were performed. The existing literature on ADSC was also reviewed. Of the 18 cases, eight were from the larynx and hypopharynx, four from the oral cavity, three from the oropharynx, and three from the nasal cavity. Three cases (16%) showed both high risk HPV E6 and E7 and p16 expression, one from the nasal cavity and two from the oropharynx. Both oropharyngeal carcinoma patients were alive and disease free at 34 and 103 months, respectively. ADSCs of the head and neck are a heterogeneous group of tumors. A small minority of cases harbor HPV and most of these, particularly those occurring at sites with known high prevalence of HPV, show active viral transcription with detectable E6 and E7 and overexpression of p16. The HPV-related oropharyngeal cases, though rare, appear to do very well clinically, while the remaining cohort of ADSC patients do quite poorly. Head and neck ADSC appears to be a mixed variant that can be further classified according to its HPV status.

Merkel cell carcinoma (MCC), an uncommon and highly aggressive cutaneous malignancy, usually occurs on the sun-damaged skin of the elderly and is characterized by coexpression of neuroendocrine markers and CK20, a discriminant from other types of visceral neuroendocrine neoplasias. Since the discovery of Merkel cell polyomavirus (MCV), many researchers have confirmed its presence in about 80% of cutaneous MCCs.1 Although some cutaneous MCCs were reported to be associated with squamous cell carcinomas (SCCs), such combined cases accounted for only a minor portion and the viral status appeared to be different from pure MCC.

Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma has unique biology and better outcomes. p16 immunostaining is used as a surrogate marker for transcriptionally active HPV. Although diffuse staining is generally accepted as positive, the significance of partial staining has not been established, nor has the cutoff for extent of p16 staining that should be used to identify a tumor as HPV-related. From three other large studies utilizing p16 immunohistochemistry, we identified all cases with partial positive staining. The p16-stained slides were reviewed by three study pathologists for staining (nuclear and cytoplasmic) extent (in quartiles), and also for percentage that was confluent (ie, back-to-back cell staining). Tumors were histologically typed (keratinizing, non-keratinizing, or non-keratinizing with maturation) and tested for high-risk HPV by RNA in-situ hybridization and reverse-transcriptase PCR. For the 16 cases, there were two 4+(13%), five 3+(31%), six 2+(38%), and three 1+(19%) p16 staining tumors. Extent of staining ranged from 5 to 90% of cells positive with 25% or more confluent staining in 4/16 (25%). Of the 16 (31%) cases, 5 were HPV-related on the basis of RNA in-situ hybridization and reverse-transcriptase PCR. All of these cases had >50% p16 staining, 4/5 (80%) had more than 25% confluent staining, and 4/7 (57%) had non-keratinizing histological features. Only one of the p16 1+/2+ tumors was HPV RNA-positive (by reverse-transcriptase PCR only and low level). All 1+/2+ cases were keratinizing type or undifferentiated. By sensitive detection methods, most partial p16-positive squamous cell carcinoma cases with >50% staining harbor transcriptionally active HPV, and most HPV+ tumors have significant amounts of confluent staining. Cases with <50% p16 staining and lacking significant confluent staining rarely harbor HPV. These results support that greater than 75% p16 staining or, alternatively, >50% staining combined with >25% confluent areas, are suitable cutoffs for defining positivity.