What is causing the erythematous patches on both of her arms?
A 62-year-old female presents for evaluation of 2 erythematous patches around 6 mm to 8 mm on the sun-exposed portions of each forearm that were asymptomatic and present for a few months. No history of bleeding or pain. She is concerned due to the persistence of the lesions, as well as her own history of sun exposure. The rest of the exam is unremarkable; she reports no changes in medication or sunscreen.
The right arm shows a well-defined erythematous, slightly palpable, 8 mm flat papule that is not tender.
What could be the cause of the patch on her right arm?
A. Actinic keratosis
B. Seborrheic keratoses
C. Bowen’s disease or squamous cell carcinoma in situ
D. Lichenoid keratosis
E. Superficial basal cell carcinoma
The left arm shows a poorly-defined erythematous, slightly palpable, 6 mm crusted flat papule that is not tender.
What could be the cause of the patch on her left arm?
A. Actinic keratosis
B. Seborrheic keratoses
C. Bowen’s disease or squamous cell carcinoma in situ
D. Lichenoid keratosis
E. Superficial basal cell carcinoma
(Answer and discussion on next page)
Answer—Right Arm: Benign lichenoid keratosis
Benign lichenoid keratosis, otherwise known as lichen planus-like keratosis, is a common lesion that is often confused with cutaneous malignancy. The average age at presentation is 59.5 years, with an age range of 36 to 87 years.1 It presents more frequently in females—76% female vs 24% male. The trunk was the most common location (76%), followed by the extremities (33%) and head and neck (7%).1 Most patients present with <3 lesions, which should be considered benign.
Answer—Left Arm: Actinic keratosis
Actinic keratoses (AKs) emerge as ill-defined pink to skin-colored, scaly papules and small plaques on chronically sun-exposed areas of light skinned individuals. It has been reported that 60% of squamous cell carcinoma (SCC) arise from AKs.2 A yearly incidence rate of SCC of 0.24% among people with multiple AKs (average of 7.7 lesions) has been shown. It has been mathematically determined that 6% to 10% of patients with multiple AKs will develop a SCC within a 10-year span, thus making it a reasonable endeavor to treat AKs.2
Both Arms
Both lesions (left and right arms) were confirmed by histology and the shave removal of each resulted in their destruction. The right lesion has the well-defined border of a lichen keratoses, while the actinic keratosis on the left arm presented with an ill-defined border. An inflamed seborrheic keratoses is a possibility, but look for classic patulous follicles. Another consideration is Bowen’s disease but the lesions are usually more keratotic. Finally, the superficial type of basal cell carcinoma is usually friable on exam and/or history, but would not be unreasonable.
References:
1. Morgan MB, Steves GL, Switlyk S. Benign lichenoid keratosis: a clinical and pathologic reappraisal of 1040 cases. Am J Dermatopathol. 2005;27(5):387-392.
2. Ibrahim SF, Brown MD. Actinic keratoses: a comprehensive update. J Clin Aesthet Dermatol. 2009;2(7):43-48.