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Successful Treatment of Parakeratosiswith 585 nm Pulsed Dye Laser IrradiationTina S. Alster, MDChristopher A. Nanni, MD

Porokeratosis, a keratinization and fibroblast cuta-neous disorder, is a progressive disease with limitedtreatment options. We describe a case of linear poro-keratosis that responded favorably to a series of 585nm pulsed dye laser treatments. In addition to its vas-cular specificity, the pulsed dye laser presumablyproduces a direct effect on collagen, as well as anindirect effect on histamine and mast cells that couldaccount for the clinical changes seen in our patient.

P orokeratosis is a disorder of epidermal keratiniza-tion and dermal fibroblast function that occurs inseveral different clinical varieties including clas-

sic Mibelli and disseminated superficial actinic, palmo-plantar, and linear forms. All of these variants share thecommon clinical features of a well-defined hyperkeratoticplaque with central atrophy and a peripheral keratoticridge. On histologic examination, a column of parakera-totic keratinocytes traversing the stratum corneum(cornoid lamella) is a typical finding in lesions of poro-keratosis, although it is not pathognomonic.

The cause of porokeratosis has not been firmly es-tablished, although there is evidence to suggest thatboth epidermal and dermal abnormalities playa role.DNA polyploidy and sensitivity of keratinocytes andfibroblasts to ionizing radiation have been documentedin lesional skin.'? Immune function may also playa rolein the expression of this disease: organ transplant re-cipients and patients undergoing chemotherapy havebeen reported to sustain porokeratosis.P In addition,many forms of porokeratosis have been associated withan autosomal dominant pattern of inheritance.

Lesions of porokeratosis can be exacerbated by sun-light and may exhibit the Koebner's phenomenon. Thecourse of porokeratosis is usually progressive and treat-ment frequently difficult. Patients need to be examinedregularly for the presence of neoplasms arising within

From the Washington Institute of Dermatologic Laser Surgery,Washington, DC.REPRINT REQUESTS to 2311 M Street, NW, Suite 200. Washington,DC 20037 (Dr. Alster).

FIGURE 1. Dorsal aspect of the hand shows characteris-tic annular plaques with erythema and scale (the lesionsextended to the upper arm in a linear pattern).

porokeratotic lesions, particularly squamous cell andbasal cell carcinomas and Bowen's disease."

Case ReportA 49-year-old woman exhibited linear, .hyperpig-mented, and erythematous annular plaques extendingfrom the dorsal surface of the right hand to the upperarm (Figure 1). The lesions first appeared at the age of2, after she sustained a thermal bum to her right arm.Prior treatments with topical corticosteroids and cryo-therapy were unsuccessful. The patient had mildhypertension, but was otherwise healthy. Her familyhistory was noncontributory. Histologic examination ofa cutaneous biopsy was consistent with the clinical di-agnosis of porokeratosis.

Treatment was initiated with a 585 nm flashlamp-pumped pulsed dye laser (SPTL-IB, Candela Laser Cor-poration) at an energy density of 6.5 J/cmz using a 5 mmspot size. Six weeks afrer the initial treatment, the lesionwas noted to be lighter in color and less hyperkeratotic.After 'a second treatment, the proximal portion of the

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FIGURE 2. Clearance of lesions after six pulsed dyelaser treatments at bimonthly intervals (fluence = 6.5 to6.75 J/cm2

, 5 to 7 mm spot size).

right upper extremity responded with almost completeresolution of scaling and was significantly less erythema-tous. Subsequent laser treatments at bimonthly intervalswithout adjunctive therapies resulted in continued im-provement; the distal portion of the upper extremity re-sponded more slowly than the proximal sections. After atotal of six laser treatments (fluence = 6.5 to 6.75 ]/cm2,

5 to 7 mm spot size), all lesions were clinically resolved(Figure 2). No lesional recurrence was noted 11 monthsfollowing the final treatment.

CommentsLinear porokeratosis is a cutaneous disorder of both epi-dermal and dermal origin. As is true with other similardisorders of keratinization, a dynamic process mediatedby genetics, immunology, and environment drives theultimate clinical expression and severity of the disease.

Treatment options for porokeratosis have includedtopical 5-fluorouracil, topical corticosteroids, excision,cryotherapy, and electrodesiccation. All have generallybeen unsuccessful in achieving remissions or have re-sulted in excessive scarring. Recent success with 585nm flashlamp-pumped pulsed dye treatment of inflam-matory linear verrucous epidermal nevi and psoriasisprovided the rationale for attempting laser treatment

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of linear porokeratosis.?" All of these conditions arecharacterized by excessive epidermal growth patternsand dermal inflammation. The increased vasculatureseen in these conditions serves as the primary target forthe vascular-specific wavelength of the pulsed dye laser.Thus, not surprisingly, a reduction in erythema is ob-served after laser irradiation.

The vascular effect of pulsed dye laser treatmentmay also influence vessel permeability, leading to a de-crease in inflammation associated with this condition.While the cause remains unclear, the improvement inskin texture and decrease in scale formation may berelated in some way to the increased tissue mast cellconcentration previously observed in pulsed dye laser-irradiated skin. 10

REFERENCES1. Reed RJ, Leone P: Porokeratosis: a mutant clonal keratosis of

the epidermis. Arch Dermatol10l: 340-347, 1970.2. Imakado S, Otsuka F, Ishibashi Y, et al: Abnormal DNA ploidy

in cells of the epidermis in a case of porokeratosis. Arch Der-mato1124: 331-332, 1988.

3. Watanabe R, Ishibashi Y, Otsuka F: Chromosomal instabilityand cellular hypersensitivity to x-radiation of cultured fibro-blasts derived from porokeratosis patients' skin. Mutat Res 230:273-278, 1990.

4. Manganoni AM, Facchetti F, Gavazzoni R: Involvement ofepidermal Langerhans cells in porokeratosis of immunosup-pressed renal transplant recipients. ] Am Acad Dermatol 21:799-800, 1989.

5. Barnett JH: Immunosuppression: a cause of porokeratosis? ]Am Acad Dermatol13: 75, 1985.

6. Sasson M, Krain AD: Porokeratosis and cutaneous malignancy:a review. Dermatol Surg 22: 339-342, 1996.

7. Alster TS: Inflammatory linear verrucous epidermal nevus:successful treatment with the 585 nm flashlarnp-purnpedpulsed dye laser. ] Am Acad Dermatol31: 513-514, 1994.

8. Ros AM, Garden JM, Bakus AD: Psoriasis response to thepulsed dye laser. Lasers Surg Med 19: 331-335, 1996.

9. Zelickson BD, Mehregan DA, Wendelschfer-Crabb G, et al:Clinical and histologic evaluation of psoriatic plaques treatedwith a flashlamp pulsed dye laser. ] Am Acad Dermato135: 64-68,1996.

10. Alster TS, Williams CM: Treatment of keloid sternotomy scarswith 585 nm flashlamp-pumped pulsed-dye laser. Lancet 345:1198-1200, 1995.