Bathing Suit Ichthyosis
A fascinating temperature-sensitive TGM1 mutation. Scaling affects only the trunk and flexures — exactly where the body is warmest. Limbs and face are largely spared.
The TGM1 mutation in bathing suit ichthyosis creates an enzyme that is temperature-sensitive — it functions normally at cooler temperatures (<35°C) but fails at body core temperature (37°C). The trunk is warmer than the limbs.
Scaling affects the trunk (chest, abdomen, back), flexures (armpits, groin), and neck. Arms, legs, face, scalp, palms, and soles are relatively normal.
The striking distribution is a major diagnostic clue. Confirmed by skin biopsy, temperature-sensitivity testing (in research settings), and TGM1 genetic sequencing for specific variants.
Essentially the same as for lamellar ichthyosis on the affected areas. Cooling the body core (cool baths, cooling vest) can temporarily reduce scaling. Acitretin is often effective.
Daily Skincare Routine
Focus intensive treatment on the trunk and flexures. Limbs need only standard moisturising.
- Cool or tepid shower (15–20 min) — Cooler than normal body temperature helps the TGM1 enzyme function temporarily, reducing scale formation. This is uniquely beneficial in bathing suit ichthyosis.
- Gentle scale removal on trunk — Wet flannel or soft sponge on trunk and flexures while still in shower.
- Apply keratolytic to trunk/flexures — Urea 20–40% cream to chest, abdomen, back, and flexures. Let absorb 2–3 min.
- Apply emollient everywhere — Diprobase or Epaderm to full body. Lighter application on limbs which are less affected.
- Cool clothing if possible — Light cotton or moisture-wicking fabric next to trunk. Reduces body temperature slightly.
- Cool or tepid bath (20–25 min) — Below 35°C. Cool baths are more beneficial in bathing suit ichthyosis than in other types. Add bath oil (Oilatum).
- Scale removal on trunk — More thorough in the evening. The cooling bath has maximised scale loosening.
- High-strength keratolytic — Urea 40% or salicylic acid 6% on the worst truncal areas. Less on flexures due to sensitivity.
- Full emollient application — Epaderm ointment on trunk; lighter product on limbs and face.
- Sleep cool — Cool bedroom, light cotton bedding. Reducing body temperature overnight reduces scale formation on the trunk.
Cooling is uniquely effective in bathing suit ichthyosis because it temporarily restores TGM1 enzyme function at the skin surface:
- Cool shower before any important event — Skin will appear visibly less scaled for 1–2 hours after a cool shower
- Cooling vest — Available via dermatologist prescription. Particularly useful in summer when trunk temperature rises
- Air conditioning — Keeping indoor temperature at 18–20°C meaningfully reduces trunk scaling
- Cold packs or gel wraps — Applied to trunk before events — an unusual but effective strategy
- Swimming — Swimming in cool pools is particularly beneficial. Chlorine drying can be countered with immediate post-swim emollient.
Medications
| Drug | Type | Efficacy | Side Effects | Notes |
|---|---|---|---|---|
| Acitretin (Neotigason) | Systemic retinoid (Rx) | 80% | Dry lips, teratogenic | Most effective systemic option. Same as for lamellar. Requires monitoring. |
| Urea 40% cream | Keratolytic (OTC/Rx) | 75% | Stinging initially | For trunk and flexural areas. Key topical treatment. |
| Emollients (Epaderm, Diprobase) | Emollient (OTC/Rx) | 65% | None | Trunk-focused application. Lighter on unaffected areas. |
| Salicylic acid 2–6% | Keratolytic (Rx) | 65% | Irritation; avoid in flexures | Careful use near flexures — easily irritated skin |
Unique Challenges and Solutions
- Air conditioning is near-essential in summer for bathing suit ichthyosis
- Cool showers throughout the day
- Cooling vest during outdoor activities
- Avoid hot environments (saunas, very hot cars)
- Increase emollient and keratolytic frequency in summer
- Consult dermatologist about increasing acitretin dose in summer (if appropriate)
- Flexural areas (armpits, groin, under breasts) are more sensitive to keratolytics — use lower strength or apply less frequently
- Zinc oxide paste to reduce friction in flexures
- Breathable underwear — cotton or bamboo. Avoid tight elastic waistbands over scaling areas
- If flexural skin breaks down: seek GP review promptly
Many dermatologists will not have seen bathing suit ichthyosis. Key facts to communicate:
- It is a temperature-sensitive TGM1 variant of lamellar ichthyosis
- TGM1 gene mutation but with specific temperature sensitivity
- Management is similar to lamellar ichthyosis for the affected areas
- Cool temperatures temporarily improve the enzyme function and reduce scaling
- Referral to a specialist centre (e.g., St John's Institute of Dermatology) for full assessment is appropriate
Red Flags
- Skin infection on affected trunk areas (redness, warmth, pus, fever)
- Scaling spreading significantly to previously unaffected areas — reassess diagnosis
- Flexural skin breakdown not responding to simple measures within 5–7 days
- No improvement with acitretin after 12–16 weeks — review with specialist