A 79-year-old man presented with a long-standing history of skin discoloration and tumors persisting for over 10 years. His medical history includes previous diagnoses of squamous cell carcinoma on the chest and multiple instances of Bowen's disease. The patient reports occasional dryness and itching of the skin, although he experiences no other significant symptoms related to his dermatological condition.

In addition to his skin issues, the patient has a medical history notable for hypertension, chronic hepatitis B virus infection, and a demyelinating disease affecting the central nervous system. He also has a past history of psoriasis, which he managed with a traditional herbal oral medicament.

Questions: 

1. What is the name of the signs associated with these cutaneous findings?

2. Which areas of the patient's body should we examine for typical skin lesions?

3. What is the recommended management for this patient?

โดย ร.อ.ยุทธรัตน์ สุวรรณชาติกุล อาจารย์หน่วยตจวิทยา กองตรวจโรคผู้ป่วยนอก 

รพ.ภูมิพลอดุลยเดช กรมแพทย์ทหารอากาศ

ANSWERs

1. Name of the signs associated with these cutaneous findings

• Raindrops on a dusty road

2. Areas of the patient's body we should examine for typical skin lesions

• Palms, soles, and other sun-exposed areas of the body

3. The recommended management for this patient

• Routine skin cancer screenings, sun protection, oral retinoids, oral nicotinamide supplementation, identify and eliminate the source of arsenic exposure

       Arsenical keratosis is a skin condition resulting from arsenicosis, which occurs when arsenic is ingested in amounts exceeding safe limits for at least six months. The onset of skin lesions can vary significantly, ranging from 4 to 40 years, depending on factors such as the type of arsenic, the method and frequency of exposure, and the dosage involved.

Common sources of arsenic exposure include:

1. Contaminated groundwater: This occurs through the consumption of well water used for drinking, cooking, and irrigation.
2. Food crops: Crops cultivated in arsenic-contaminated soil or irrigated with tainted water can accumulate arsenic, with whole-grain rice containing higher levels than polished rice.
3. Traditional medicines: Arsenic is also found in some Chinese and Ayurvedic herbal remedies.
4. Occupational exposure: Industries that manufacture alloys, pigments, textiles, glass, paper, and wood preservatives, as well as workers in metal smelting and mining, face higher arsenic exposure risks. Communities near these operations are similarly at risk.

       Physical examination, multiple yellowish to pigmented hyperkeratotic papules and plaques are observed, beginning at pressure points on the palms and soles. As the condition advances, these lesions increase in size, number, and thickness, potentially merging into large, wart-like plaques. The involvement may spread diffusely across the palms, soles, and other areas of the body.

       Patients often exhibit pigmentary changes, including generalized hyperpigmentation or patchy discoloration, especially in skin folds. Two notable pigmentation patterns include symmetrically distributed hyperpigmented macules resembling a "raindrop pattern" and guttate hypopigmentation against a background of hyperpigmentation, likened to "raindrops on a dusty road." Oral mucosal pigmentation may also occur.

       Patients with arsenical keratosis may develop lesions such as Bowen's disease, squamous cell carcinoma (SCC), and basal cell carcinoma on both exposed and unexposed skin.

       Chronic arsenic toxicity affects multiple systems, with patients possibly experiencing chronic liver and lung diseases, neuropathy, peripheral vascular issues, ischemic heart disease, chronic kidney disease, and gastrointestinal symptoms like anorexia, dyspepsia, and diarrhea.

       Patients are advised to quit smoking and maintain a well-balanced, high-protein diet. Antioxidant supplements, such as vitamins A, C, and E, may also aid in cancer prevention. While treatment for arsenical keratosis is not strictly necessary, supportive care is essential to alleviate discomfort. Various treatment options that have been explored include cryotherapy, carbon dioxide laser ablation. For patients with extensive lesions, a combination of acitretin and topical keratolytics may be beneficial and could provide chemoprevention against cancers related to chronic arsenic exposure.

Reference:

• Shajil C, Chen P, Mahabal GD. Arsenical keratosis. StatPearls. Treasure Island (FL): StatPearls Publishing; 2024.
• Mainville L, Smilga A-S, Fortin PR. Effect of nicotinamide in skin cancer and actinic keratoses chemoprophylaxis, and adverse effects related to nicotinamide: A systematic review and meta-analysis. J. Cutan. Med. Surg. 2022;26(3):297–308.

โดย ร.อ.ยุทธรัตน์  สุวรรณชาติกุล อาจารย์หน่วยตจวิทยา กองตรวจโรคผู้ป่วยนอก

รพ.ภูมิพลอดุลยเดช กรมแพทย์ทหารอากาศ