Introduction
Porokeratosis is a clonal disorder of keratinization defined by the presence of a cornoid lamella. Facial involvement is uncommon, and isolated lesions on the nasal ala are particularly rare and often mimic actinic or inflammatory dermatoses. Chronic ultraviolet exposure is a frequent contributing factor.1, 2, 3
We report a case of localized nasal porokeratosis in an elderly patient with long-term sun exposure, highlighting the clinicodermoscopic features and successful treatment with alternating topical calcipotriene and 5-fluorouracil.
Case presentation
A 73-year-old male farmer presented with a solitary, asymptomatic plaque on the left nasal ala that had slowly enlarged over 6 months. The lesion measured 1.2 cm and exhibited a slightly atrophic, hypopigmented center with a raised keratotic border [Fig 1]. There was no pain, pruritus, bleeding, trauma, or previous treatment. The patient reported more than 4 decades of occupational sun exposure. Dermoscopy revealed a sharply demarcated whitish keratotic rim with prominent follicular plugging surrounding a central structureless whitish area, a pattern suggestive of porokeratosis [Fig 2].
Fig 1.
Clinical image showing a solitary, well-defined annular plaque with a keratotic rim and slightly atrophic center located on the left nasal ala of a 73-year-old man. The lesion had been present for 6 months and was asymptomatic.
Fig 2.
Dermoscopy demonstrating a sharply demarcated whitish keratotic border with prominent follicular plugging and slightly atrophic area — features consistent with porokeratosis.
A punch biopsy taken from the peripheral border—where the cornoid lamella is best visualized—confirmed the diagnosis. Solar elastosis was present in the dermis, consistent with chronic photodamage. Given the cosmetically sensitive location, destructive modalities such as cryotherapy, curettage, or laser ablation were avoided.
The patient began an alternating-day regimen of topical calcipotriene 0.005% ointment and 5% 5-fluorouracil cream, applied once daily on separate days for 4 weeks. Mild crusting developed during the first week and resolved spontaneously. By 1 month, the lesion showed marked improvement with flattening of the border and resolution of central atrophy. Complete clinical clearance was achieved at 6 weeks, and no recurrence was noted at the 3-month follow-up. The area healed with minimal residual atrophic scarring [Fig 3].
Fig 3.
Post-treatment photograph after 1 month of alternating-day therapy with topical calcipotriol and 5-fluorouracil, showing complete clearance of the lesion with minimal residual atrophic scarring and no recurrence at 3-month follow-up.
Discussion
Porokeratosis is a keratinization disorder defined by the presence of a cornoid lamella. Facial involvement is uncommon, and isolated lesions on the nasal ala are rare and may resemble actinic keratosis, discoid lupus erythematosus, or Bowen disease.1, 2, 3 Clinicodermoscopic evaluation, supported by biopsy from the peripheral border, is therefore helpful for accurate diagnosis in these atypical presentations.
Chronic ultraviolet exposure is a recognized contributing factor in actinic variants of porokeratosis.4,5 Although destructive modalities may be effective, they can result in scarring or dyspigmentation on cosmetically sensitive facial sites. Topical therapies are less invasive but often yield variable results.6
The combination of calcipotriene and 5-fluorouracil provides a biologically plausible therapeutic approach through a dual mechanism. Calcipotriene increases expression of thymic stromal lymphopoietin, promoting a localized T-cell–mediated immune response, whereas 5-fluorouracil induces apoptosis in atypical or dysplastic keratinocytes.7,8 This coordinated immune activation and cytotoxic effect may enhance clearance while limiting local inflammation.
In our patient, an alternating-day regimen (calcipotriene 0.005% ointment once daily on odd days and 5-fluorouracil 5% cream once daily on even days) for 6 weeks resulted in complete resolution without significant irritation, scarring, or postinflammatory dyspigmentation. No recurrence was observed at the 3 month follow-up.
These findings suggest that the dual immunomodulatory–cytotoxic mechanism may be particularly useful for localized actinic porokeratosis in areas where tissue-sparing therapies are preferred. Additional reports and prospective studies will help further define the role of this combination across porokeratosis subtypes.
Conclusion
This case adds to the scarce literature on isolated nasal porokeratosis and illustrates the value of integrating clinical, dermoscopic, and histopathologic findings for diagnosis. The favorable response to alternating topical calcipotriene and 5-fluorouracil supports its consideration as a tissue-sparing option for localized actinic lesions in cosmetically sensitive areas, and additional observations may help define its broader clinical role.
Conflicts of interest
None disclosed.
Footnotes
Funding sources: None.
Patient consent: The authors obtained written consent from patient for their photographs and medical information to be published in print and online and with the understanding that this information may be publicly available. Patient consent forms were not provided to the journal but are retained by the authors.
IRB approval status: Not applicable.
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