Terra firma-forme dermatosis sounds like a frightening diagnosis that no parent would want their kid to have. Thankfully, it is actually quite the opposite. Even though it has a very unique name, the benign nature of this condition should not cause alarm.
Last summer, I noticed a dark brown spot on my 9 year old daughter’s neck. It had not been too long before that she started showering independently under her own direction. My hunch was that she had some dirt on her neck that she was missing during her bathing sessions.
However, even after she insisted that she scrubbed the area during her last shower, this dirty-appearing skin persisted.
That’s when it hit me. I remembered another doctor mentioning something similar in one of our physician Facebook groups. A dermatologist in the group commented that the likely diagnosis was terra firma-forme dermatosis and that the skin lesion should have complete resolution after using an alcohol swab on the area.
Sure enough, the spot disappeared after cleaning it with an isopropyl alcohol pad.
Terra Firma-Forme Dermatosis
The clinical presentation of the interesting skin condition is classic. Normally, it shows up as a patch of slightly thickened brown or black skin. The cause for this condition is not completely clear, but is it hypothesized to be delayed keratinization (or formation of the waterproof protein layer of skin).
The keratinocytes make their final home in the stratum corneum layer of skin.
Delay in adhesion of keratinocytes or sticking together of these skin cells can lead to accumulation of dirt and other skin waste cells. This condition is also known as dirty dermatosis or dermatosis neglecta due to these adherent cells trapping dirt, germs and accumulation of sebum (oil) leading to cutaneous discoloration.
The age of onset of this condition is around 10 years of age and mostly occurs in pre-pubertal children.
Diagnosis and Treatment
Amazingly, both the diagnosis and treatment are the same.
Cleaning the area with a 70% isopropyl alcohol wipe or gauze soaked in the alcohol will both treat and diagnose the lesion.
What else could it be?
Terra Firma Forme Dermatosis can be confused with other common skin conditions. Our skin is the largest organ in our bodies and can show the evidence of other diseases so sometimes we have to dig deeper for the answers.
Many medical conditions such as ulcerative colitis or other inflammatory bowel disease, autoimmune and rheumatolgoical diseases and renal failure can have cutaneous eruptions that may be confused with terra firma forme dermatosis at first.
Additionally, the dark layer of skin that accumulates on the neck and axillary (arm pit) folds of adults and children who have higher body weight or have diabetes is called acanthosis nigricans. It can be confused with terra firma forme. The difference is that acanthosis does not wipe off with alcohol like terra firma forme does.
Is This a Life-Threatening Disease?
Although the name sounds scary, thankfully terra firma forme dermatosis is not life threatening. Often, it occurs once and resolves with treatment quickly.
Frequently children with this condition don’t even make it into the pediatrician’s office because their astute parents recognize this lesion and treat it at home.
What if you could text a picture to your child’s doctor?
If you are a member of 127 Pediatrics, you can always send me a text with a picture of any skin lesion that you are worried about. Schedule a free meet and greet today to see if 127 Pediatrics is right for your family.
© 127 Pediatrics; September 2023
This article is for informational purposes only and should not be construed as medical advice.
Dr. Andrea Wadley is the owner, pediatrician, and breastfeeding medicine specialist for 127 Pediatrics. She has an established house-calls-only concierge pediatric practice in Colleyville, TX. She is also the owner and operator of the 127 Pediatrics Online Breastfeeding Medicine and Education Center.
