Terra Firma-Forme Dermatosis Misdiagnosed as Nevoid Acanthosis Nigricans

Abstract

Terra firma-forme dermatosis (TFFD) is a clinical condition characterized by brown-gray, velvety, pigmented patches or plaques, resembling dirt on the skin. Nevoid acanthosis nigricans (NAN) is a rare and recently described form of acanthosis nigricans occurring during childhood or early adulthood. Herein we describe a patient with TFFD, initially misdiagnosed as NAN. The patient had developed hyperkeratotic and hyperpigmented plaques on and around the umbilicus during pregnancy. Though regular in bathing practices, she could not clear away the lesions and concerned marks for inesthetic appearance. Histopathological findings were compatible with NAN, and she was prescribed 10% urea lotion. On a dramatic healing after 3 weeks, a diagnosis of TFFD is considered and confirmed by the lesions getting wiped away by vigorous rubbing with alcohol pads. We discuss the key points of differentiating TFFD from NAN, and underline the importance of alcohol test for accurate diagnosis.

Terra firma‐forme dermatosis: a systematic review

“…The most commonly reported features were prominent lamellar hyperkeratosis, focal areas of compact whorled orthokeratosis (lack of parakeratosis), keratin whorls and globules in the stratum corneum, acanthosis, papillomatosis, and hypermelanosis within the basal layer and the hyperkeratotic areas. Mild perivascular lymphocytic infiltration in the superficial dermis was found in five reports 18,23,35–37 . PAS stains evidenced fungal elements in the stratum corneum in seven studies, 11,15,31–34,36 while another paper did not detect any superficial spores or hyphae 23…”

“…The title and abstract of the 102 items were screened, and 69 were considered eligible for full‐text assessment. Of the 69 studies, 64 were included in the systematic review 1–63 . The studies were published between 1987 and 2020.…”

“…Overall, the records of 22 patients reported a diagnostic pitfall prior to the diagnosis of TFFD (Table 4). The two most common misdiagnoses were AN 14,25,35,39 and mycosis 11,16,27,34 (each accounting for 31.8% of cases), followed by eczema (including atopic eczema in 1 case, 18.2%), 14,47 lichen simplex chronicum 46 (4.5%), vulgar ichthyosis 16 (4.5%), pseudo‐acanthosis nigricans 30 (4.5%), and atypical nevus 48 (4.5%).…”

Terra Firme-Forme Dermatosis Diagnostic Sign and Treatment: A Case Report

“…An association with atopic dermatitis and xeroderma has been reported [3]. Even though TFFD was reported in association with pregnancy [7], it can be assumed that there is no etiological association, but simply a higher rate of detection during this phase of life. The possibility for a syndromic disease has been postulated, which will remain disputed though until further evidence arises [8, 9].…”

Erworbene retikuläre Pigmentdermatosen

“…Histologisch lassen sich ähnlich der PCR Hefesporen nachweisen und Hyperkeratose, Papillomatose, Akanthose sowie wirbelige Orthokeratose beobachten [49]. Hochcharakteristisch ist, dass die Hyperpigmentierungen mit 70 %igem Alkohol weggewischt werden können; durch diese diagnostisch-therapeutische Maßnahme kann die Erkrankung auch von klinisch ähnlichen Fällen einer AN abgegrenzt werden [48,50]. Eine Assoziation zur atopischen Dermatitis wird angenommen [51].…”