A Long‐Standing Palmar Depressed Macule

An 81-year-old woman with no relevant medical history presented with a 15-year history of a slowly enlarging, erythematous macule on the thenar eminence of the right hand, occasionally pruritic. Previous topical antifungal treatments had failed. Physical examination: a single 1 × 2 cm erythematous, depressed macule with a hyperkeratotic border (Figure 1). Dermoscopy revealed a stepped border, peripheral scaling, dotted vessels, and linear white dots on an erythematous background (Figure 2). A biopsy was obtained from the edge of the lesion (Figure 3). Circumscribed palmar hypokeratosis (CPH) Histopathological examination showed abrupt thinning of the stratum corneum ('stair pattern'), orthokeratosis, eosinophilic corneocytes; in the papillary dermis, there were dilated vessels and slightly thickened collagen fibers. Laboratory tests were otherwise unremarkable. CPH is a rare benign entity, predominantly affecting women in the fifth to eighth decades of life. The classical sites are the palms, particularly the thenar and hypothenar regions, and less frequently the soles. Lesions are usually chronic, solitary, erythematous, slightly depressed, with well-defined scaly borders, and have an average duration of 12–15 years, as in the present case 1, 2. Dermoscopically, CPH is characterized by a stepped border, peripheral scaling, dotted vessels, white dots, and rosette structures corresponding to acrosyringia on an erythematous base. These features help differentiate CPH from clinically similar entities, such as porokeratosis, Bowen's disease, or punctate keratolysis 3-5. Histopathologically, there is abrupt thinning of the stratum corneum with hypogranulosis and orthokeratosis, eosinophilic corneocytes, and absence of cellular atypia. Subtle dermal changes include dilated vessels and thickened collagen fibers 6, 7. Several theories on the pathophysiology have been proposed, but the most accepted involves an aberrant epidermal clone with altered expression of cytokeratins 10 and 16, increased Ki-67, and corneocyte defects, resulting in stratum corneum thinning. This excludes an association with human papillomavirus 6, 7. Although CPH is benign, isolated cases of progression to actinic keratosis or squamous cell carcinoma in situ have been reported, highlighting the importance of follow-up 3, 6. No standardized treatment exists. Options described include cryotherapy, surgery, photodynamic therapy, topical corticosteroids, calcipotriol, and 5-fluorouracil, with variable outcomes 1, 2. Our patient received two cycles of 10-s liquid nitrogen cryotherapy. After 4 weeks, erythema was reduced, although the patient could not tolerate further sessions; clinical follow-up was continued. Cryotherapy is considered an effective therapeutic option; however, when performed on large lesions, it may be painful if applied to the entire area at once. Local anesthesia or a staged, area-by-area approach may improve tolerance 6-8. CPH is a rare entity requiring correlation of clinical, dermoscopic, and histopathological findings for diagnosis and differentiation from premalignant lesions. No standardized treatment exists; management should be individualized with careful long-term follow-up. Jhon Edwin Rodríguez-Vásquez: conceptualization, acquisition of data, writing original draft preparation. Gadwyn Sánchez-Félix: investigation, conceptualization, acquisition of data, final manuscript approval. Alan Jesús Latorre-Zúñiga: interpretation of histopathological studies of the skin. Reynaldo Alberto Pomar-Morante: supervision, investigation. Celia Betzabet Moisés-Alfaro: supervision. The authors received no specific funding for this work. All patients in this manuscript have given written informed consent for participation in the study and the use of their de-identified, anonymized, aggregated data and their case details (including photographs) for publication. Ethical Approval: not applicable. The authors declare no conflicts of interest. Data sharing not applicable to this article as no datasets were generated or analyzed during the current study. The data that support the findings of this study are available from the corresponding author upon reasonable request.