Large Cell Acanthoma

 Proliferation of atypical keratinocytes typically confined to basilar 1/3 of epidermis


image Overlying parakeratosis and basilar budding usually seen


• Solar lentigo (lentigo senilis)
image Elongated, hyperpigmented rete ridges

image Lacks keratinocyte atypia/pleomorphism

• Seborrheic keratosis
image More prominent epidermal acanthosis with pseudohorn cysts



image
Large Cell Acanthoma
LCA shows an intraepidermal proliferation of enlarged keratinocytes image in a disorganized pattern. There is no basilar budding or overlying parakeratosis typical of an actinic keratosis. Note the prominent solar elastosis image in dermis.


image
Large Cell Acanthoma at High Magnification
Higher power of LCA shows enlarged keratinocytes image involving the mid to upper layers of epidermis with overlying basket-weave orthokeratosis. The dermis shows solar elastosis and mild chronic inflammatory infiltrate image.

image
Large Cell Acanthoma at Low Magnification
Another example of LCA shows an intraepidermal proliferation of enlarged squamous cells image. There is a lack of basilar budding or overlying parakeratosis typical of actinic keratosis.

image
Large Cell Acanthoma at High Magnification
The cells show nuclear enlargement, hyperchromasia, and focally prominent nucleoli image, but no mitotic figures are identified.


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)
image Has been variously considered to be related to or variant of solar lentigo, seborrheic keratosis (stucco keratosis) (SK), 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

Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Large Cell Acanthoma
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