Large Cell Acanthoma
David Cassarino, MD, PhD
Key Facts
Terminology
Proliferation of enlarged and mildly atypical keratinocytes in sun-damaged skin without diagnostic features of actinic keratosis
Variously considered to be related to solar lentigo, seborrheic keratosis, or actinic keratosis
Etiology/Pathogenesis
Most cases associated with UV radiation
HPV types have been detected in some studies
Clinical Issues
Typically occur in older adults (mean age: 75 years)
Usually head and neck region or extremities
Microscopic Pathology
Epidermal acanthosis with proliferation of enlarged keratinocytes with proportionately enlarged nuclei
Overlying hypergranulosis and hyperkeratosis usually present
Mitotic figures rare
 LCA shows an intraepidermal proliferation of enlarged keratinocytes in a disorganized pattern. There is no basilar budding or overlying parakeratosis typical of an actinic keratosis. Note prominent solar elastosis  in dermis. |
 Higher power of LCA shows enlarged keratinocytes  involving the mid to upper layers of epidermis with overlying basket-weave orthokeratosis. Dermis shows solar elastosis and mild chronic inflammatory infiltrate. |
TERMINOLOGY
Abbreviations
Large cell acanthoma (LCA)
Definitions
Proliferation of enlarged and mildly atypical keratinocytes in sun-damaged skin without diagnostic features of actinic keratosis (AK)
Has been variously considered to be related to or a variant of solar lentigo, seborrheic keratosis (stucco keratosis), or AK
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Most cases associated with UV radiation (chronic solar damage)
Infectious Agents
HPV types have been detected in some studies
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