HPV detection in 'large-cell acanthomas': a word of caution

Human Papillomavirus-Associated Giant Clear Cell Acanthoma and Squamous Cell Carcinoma: A Rare Case Report and Literature Review

Clear cell acanthoma (CCA) and squamous cell carcinoma (SCC) represent distinct entities within dermatological oncology, each posing unique diagnostic and therapeutic challenges. CCA is a rare, benign epidermal growth, often not associated with human papillomavirus (HPV) infection, whereas SCC, a more aggressive form of skin cancer, has been linked to both ultraviolet (UV) exposure and HPV. Understanding the co-occurrence of these conditions in a single patient can enhance diagnostic accuracy and therapeutic outcomes. We report a 64-year-old male who underwent an operation for a verruciform lesion in the right groin, which was diagnosed as HPV-positive CCA alongside keratinised SCC. A literature search across January 2024 revealed limited evidence directly linking HPV to CCA, suggesting a need for further investigation. The speculative association between HPV and CCA warrants deeper exploration, especially considering the potential for HPV to contribute to lesion development through indirect mechanisms. The coexistence of CCA and SCC in an elderly patient presents a unique clinical scenario. This emphasises the need for vigilant diagnosis and tailored treatment strategies, highlighting the gap in understanding the pathogenesis of CCA, particularly its potential association with HPV. Further research is crucial for elucidating the complex interactions governing these conditions and for developing targeted interventions.

Large Cell Acanthoma of the Conjunctiva: Clinicopathologic and Immunohistochemical Features

Large cell acanthoma (LCA) was first described as a lesion on sun-exposed skin. All LCAs feature keratinocytes twice the size of normal cells (cytomegaly). Although infrequently diagnosed in the skin, it has been even more rarely described by ophthalmic pathologists in the eyelid skin and the conjunctiva. This report describes the third case of a conjunctival epithelial LCA, with the first published clinical photograph highlighting its leukoplakic and well-circumscribed character, as well as the most thorough analysis of the immunohistochemical features of this lesion. It is contrasted with squamous dysplasias and papillomas of the conjunctiva. A review of previous conjunctival LCA lesions discloses frequent recurrences after initial surgery and the remote but real potential for squamous dysplastic transformation. Immunohistochemical stains for certain cytokeratins, p53, and Ki-67 (proliferation index) will in the future be particularly helpful in establishing an early and accurate diagnosis of conjunctival LCA.

[Anatomoclinical study of large-cell acanthoma]

BACKGROUND

Large-cell acanthoma (LCA) is a benign tumour initially described in 1970, since when it has been subject to controversy and remains poorly understood. We carried out a single-centre anatomoclinical study in order to identify the clinical and histological characteristics of the disease.

PATIENTS AND METHODS

Slides classed as LCA in our cutaneous histopathology laboratory were re-read and subjected to Melan-A and HMB45 immunohistochemical labelling. Diagnosis was based upon the presence of a clearly delineated epidermal lesion comprising keratinocytes twice as large as cells adjacent to the lesion. Clinical information was obtained through the analysis of existing requests and clinical files.

RESULTS

We identified 20 cases of LCA. Mean patient age was 70 years and the sex ratio was 0.25. The mean disease duration was 1.6 years. In most cases, a pigmented macule or papule was seen, sometimes with a verrucous surface. LCA had not been diagnosed by the clinician in any of the cases seen. In terms of histology, all lesions were clearly delineated, with hypergranulosis beneath hyperorthokeratosis, occasionally with accentuation of the papillary outline. An accentuated stratum lucidum was noted in 80% of cases. In the pigmented forms, immunohistochemical labelling showed no increase in melanocyte count.

DISCUSSION

LCA is a benign lesion that is most likely underdiagnosed since it is poorly known to clinicians and to certain pathologists. It is seen primarily in adult women and is found on the limbs and on the face. Some debate surrounds the definition of LCA as a separate entity, and some authors assimilate it with solar lentigo, but this hypothesis is countered by the existence of hypopigmented forms and we consider it to be a specific anatomoclinical entity.