Aim-To investigate whether immunohistochemical staining for cytokeratin 20 (CK20) and thyroid transcription factor 1 (TTF-1) is useful in distinguishing Merkel cell carcinomas (MCCs) from metastatic small cell carcinomas (SCCs). Methods-Eleven cases of MCC and 10 of lung SCC were stained for CK20 and TTF-1. Results-Ten of 11 MCCs stained with the antibody to CK20. None was positive for TTF-1. No SCC stained with anti-CK20 and all stained strongly with anti-TTF-1. Conclusions-The use of both anti-CK20 and anti-TTF-1 can reliably distinguish between MCC and metastatic SCC, thus avoiding the need for a detailed clinical investigation of patients with MCC in whom metastatic SCC must be excluded. (J Clin Pathol 2001;54:727-729)

No abstract

Diagnosis of vulval inflammatory disease is difficult. In this study, we reviewed 31 vulval biopsies from 23 patients with clinical follow-up. We devised 2 scoring systems from recent publications to determine whether these could help to distinguish between lichen sclerosus (LS) and lichen planus (LP). We found that scoring systems could help in distinguishing LS from LP but that they were no better than using some select pathologic criteria, and were much more time-consuming. Most cases of LS had characteristic dermal sclerosis. LP cases had a characteristic band-like inflammatory infiltrate and did not always have features such as pointed rete ridges, wedge-shaped hypergranulosis and cytoid bodies as observed in nonvulval sites. Eczema was the third most common dermatosis in the study and had features that could also be observed in LS, such as acanthosis, abnormal collagen, and ectatic blood vessels. However, dermal sclerosus was not observed. Loss of dermal elastin fibers was observed in both LS and LP and thus did not help in discriminating between the 2 conditions. Oral LP elsewhere in the body was common and was observed in 20% of both the LS and LP group. A small proportion of patients did not fit into any category. We believed that it was important not to label patients as having a disease unless specific features were observed. It may be in their best interests to be called nonspecific rather than being put in the wrong disease category.

Since 1991 infrequent reports have described a distinctive triad of nodulocystic acne, striking follicular spines and an eruption resembling pityriasis rubra pilaris (PRP) in HIV-positive patients. It has been suggested that this may represent a subtype of PRP, or alternatively that it should be viewed as a unique HIV-associated follicular occlusion triad. Clinical manifestations may be severe, and in several cases have been ultimately fatal, with death occurring due to complications of cutaneous sepsis. We describe a case demonstrating severe conglobate acne, follicular keratotic spines and histologically confirmed PRP in association with HIV infection. Clinical features and treatment modalities of previously reported cases are reviewed. Despite refusing all topical and systemic treatment our patient showed spontaneous remission of skin signs after 2 years.