[Anatomoclinical study of large-cell acanthoma].

Area of Science:

• Dermatopathology
• Oncology
• Histology

Background:

• Large-cell acanthoma (LCA) is a benign epidermal tumor with a controversial and poorly understood classification.
• Existing literature lacks comprehensive data on LCA's clinical and histological characteristics.
• The need for a clearer definition and understanding of LCA as a distinct entity is evident.

Purpose of the Study:

• To investigate and define the clinical and histological features of large-cell acanthoma (LCA).
• To assess the diagnostic accuracy and potential underdiagnosis of LCA.
• To evaluate LCA's classification as a separate entity compared to other skin lesions like solar lentigo.

Main Methods:

• Retrospective analysis of 20 cases classified as LCA in a single cutaneous histopathology laboratory.
• Re-evaluation of histological slides with Melan-A and HMB45 immunohistochemical staining.
• Clinical data collection through patient records and request forms.

Main Results:

• Twenty cases of LCA were identified, predominantly in elderly women (mean age 70, sex ratio 0.25).
• Clinical presentation typically involved pigmented macules or papules (mean duration 1.6 years), often misdiagnosed by clinicians.
• Histological findings included well-defined epidermal lesions with characteristic keratinocyte enlargement, hypergranulosis, hyperorthokeratosis, and an accentuated stratum lucidum in 80% of cases; no increased melanocytes were observed in pigmented forms.

Conclusions:

• Large-cell acanthoma (LCA) is likely underdiagnosed due to limited clinician and pathologist awareness.
• LCA presents as a distinct benign entity, primarily affecting adult women on the limbs and face.
• Despite some debate, LCA's unique features, including hypopigmented variants, support its classification as a specific anatomoclinical entity separate from solar lentigo.