Porokeratosis

A case of the hyperkeratotic variant of porokeratosis Mibelli

Herein, we report a case of the hyperkeratotic variant of porokeratosis Mibelli. A 58-year-old woman presented with two brownish verrucous plaques on the buttock for 20 years, and extremely hyperkeratotic verrucous nodules and brownish macules on the right foot for 1 year. Histopathological findings of the buttock were typical of porokeratosis. However, histopathological findings of the right foot were atypical for porokeratosis, including extreme hyperkeratosis and an increased number of and unusual sized cornoid lamellae.

A Novel Locus for Disseminated Superficial Porokeratosis Maps to Chromosome 18p11.3

Disseminated superficial porokeratosis (DSP) is a rare autosomal dominant epidermal keratinization disorder of lesions characterized by cornoid lamella with parakeratosis, hyperkeratosis, and loss of granular layers. The genetic basis for this disease is unknown. Through a proband with a diagnosis of DSP, we identified a large four-generation Chinese family with multiple DSP-affected members from Anhui province in China. After excluding the linkage of the disease phenotype to two known loci for disseminated superficial actinic porokeratosis in this family, we performed a genome-wide linkage analysis using 387 microsatellite markers and identified a novel disease locus for DSP at 18p11.3. Our subsequent fine mapping and haplotype analyses further narrowed down the disease locus into an 18.7 cM region between the telomere and D18S391 with a maximum two-point LOD (logarithm of the odds) score of 4.82 (theta =0.00) at D18S1138. Therefore, this study provides strong linkage evidence for a DSP locus at 18p11.3.

Squamous cell carcinoma in a renal transplant recipient with linear porokeratosis

A 40-year-old man developed squamous cell carcinoma on a perianal lesion of linear porokeratosis after renal transplantation. The tumor metastasized to the left inguinal lymph node 25 months after the primary tumor was excised. p53 overexpression was observed in the tumor cells, but not in the porokeratotic lesion. Interestingly, continuous subcutaneous infusion of peplomycin for the lymph node metastasis significantly improved the warty lesions of porokeratosis. In this patient, immunosuppressive agents might have accelerated the development of carcinoma on a skin area with malignant potential.

The hyperkeratotic variant of disseminated superficial actinic porokeratosis (DSAP)

A 78-year-old South Korean man was referred to us from the Medical Intensive Care Unit (MICU) for an opinion. He was comatose and was on ventilatory care due to aspiration pneumonia. Multiple tiny papules had developed 10 years previously and since then the number and size had been increasing gradually. He had been diabetic for the past 4 years, and had Parkinson's disease diagnosed 1 year previously. Laboratory examinations revealed an elevated level of white blood cells (WBCs) (25,000/microL) and decreased hemoglobin (8.8 g/dL). Other laboratory results were negative or within normal limits. Skin examination showed multiple, discrete, crust-like, brownish papules over the erythematous base on the face, upper extremities, and lower extremities. With the clinical impressions of irritated verruca vulgaris, seborrheic keratosis, or cutaneous fungal infection, a skin biopsy was taken from a papule on the left shin, and histopathologic examination revealed several pronounced hyperkeratotic and parakeratotic columns, and characteristic cornoid lamellae in the stratum corneum. Beneath the cornoid lamellae, the granular layer was decreased. A number of round or oval, dyskeratotic, homogenized eosinophilic cells with pyknotic nuclei were scattered in the prickle cell layer below the cornoid lamellae. A mild lymphohistiocytic infiltrate was observed in the papillary dermis and around the blood vessels in the upper dermis. Also, actinic degeneration was present in the upper dermis.