
==== Front
Int J Appl Basic Med Res
Int J Appl Basic Med Res
IJABMR
Int J App Basic Med Res
International Journal of Applied and Basic Medical Research
2229-516X
2248-9606
Wolters Kluwer - Medknow India

IJABMR-14-205
10.4103/ijabmr.ijabmr_162_24
Case Report
Dermatological Enigma Unveiled: A Rare Case Report on Dowling-Degos Disease
Goswami Parth Rajendragiri
Pathania Yashdeep Singh 1
Singh Gyanendra
Patel Tarang
Agarwal Ashwini 2
Department of Pathology, Venereology and Leprosy, AIIMS, Rajkot, Gujarat, India
1 Department of Dermatology, Venereology and Leprosy, AIIMS, Rajkot, Gujarat, India
2 Department of Microbiology, AIIMS, Rajkot, Gujarat, India
Address for correspondence: Dr. Parth Rajendragiri Goswami, AIIMS, Rajkot, Gujarat, India. E-mail: goswamiparth42@gmail.com
Jul-Sep 2024
24 8 2024
14 3 205207
10 4 2024
12 7 2024
15 7 2024
Copyright: © 2024 International Journal of Applied and Basic Medical Research
2024
https://creativecommons.org/licenses/by-nc-sa/4.0/ This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
Dowling-Degos disease (DDD) is an extremely rare hereditary skin condition characterized by the development of painless, small-sized pigmented patches known as macules or keratotic papules. Typically inherited in an autosomal dominant manner, DDD primarily manifests in adulthood, with onset occurring between the ages of 30 and 40 years, and a higher prevalence among females. Although DDD shares clinical similarities with other reticulated pigmentary disorders such as dyschromatosis symmetrica hereditaria, dyschromatosis universalis hereditaria, and reticulate acropigmentation of Kitamura, its distinctive histopathological features set it apart. A 50-year-old female patient presented with hyperpigmented lesions since infancy, predominantly located in flexural areas, prompting consideration of endogenous eczema or DDD. Despite the absence of a family history and normal laboratory test results, a biopsy confirmed the diagnosis based on characteristic histological findings. The identification of DDD underscores the importance of considering rare dermatological entities in differential diagnosis, especially when clinical presentation aligns with established criteria. Further research and awareness are essential for enhancing our understanding and management of this intriguing skin condition.

Dowling-Degos disease
eczema
pathology
skin histopathology
==== Body
pmcIntroduction

The rare hereditary skin condition known as Dowling-Degos disease (DDD) is inherited autosomal dominantly and has a range of expressions. Dowling-Degos illness is an extremely rare condition with an unknown prevalence. Fewer than 50 cases have been described in the literature. The onset typically occurs in maturity adulthood, specifically between the ages of 30 and 40 years. The prevalence is higher among females, with a ratio of 2:1. Lesion progress slowly over the years.[12]

DDD is an uncommon disorder characterized by the appearance of painless, small-sized, slowly forming pigmented patches called macules or keratotic papules. These spots typically appear on the armpits, groin, face, neck, torso, and arms. In addition, there may be scattered blackhead-like follicles and depressed acne-like scars. The lesions initially originate in the axillae and then extend to other parts of the body.[3]

DDD, dyschromatosis symmetrica hereditaria (DSH), dyschromatosis universalis hereditaria (DUH), and reticulate acropigmentation of Kitamura (RAPK) exhibit similar clinical characteristics. However, they differ in terms of their pathological findings.[4] DSH exhibits both hyperpigmented and hypopigmented lesions. Hyperpigmented lesions show the presence of abundant melanin pigment in keratinocytes and melanocytes with the presence of a scattered melanophages as well; while hypopigmented lesions reveal the presence of interface dermal inflammation.[5] DUH also has both hyperpigmented and hypopigmented lesions; however, hyperpigmented lesions show the presence of hyperkeratosis, basal layer vacuolation, melanin incontinence, and dilated dermal vessels.[6] The RAPK is characterized by the elongation of filiform rete ridges, hyperpigmentation of basilar keratinocytes, and the presence of melanocyte clusters near the tip of the rete ridges.[7]

The histopathological analysis of DDD commonly shows elongated rete ridges, hyperpigmented macules, melanin accumulation along the basal layer, and mild inflammation in the upper dermis. In addition, there may be elongated rete pegs, a thin and atrophic epidermis, and a reticular pattern with horn cysts.[8]

Case Report

A 50-year-old female patient visited the dermatology department of a medical college teaching institute with a complaint of hyperpigmented lesions that she has had since infancy. The patient indicated the absence of any comparable abnormalities within their family and no evidence of consanguinity. The lesions were devoid of symptoms such as pain or itching and did not disappear spontaneously. The patient does not exhibit any chronic disease, infection, smoking or alcohol habits, or medication history. Upon skin examination, the patient had numerous hyperpigmented follicular keratotic brown papules and macules about 2–4 mm in size. These skin lesions were primarily seen in the cubital fossa of the arms, groin region, buttocks, trunk, and back. The hair, nails, eyes, palms, soles, and mucous membranes appeared to be in a normal state [Figure 1].

Figure 1 Clinical image of lesions

The dermatologist identified two potential diagnoses based on the patient’s complaints and dermatological examination: endogenous eczema and Dowling-Degos illness. The results of her complete blood count, liver function test, and renal function test all fell within the normal range. Due to resource limitations and cost restraints, the mutation study of the keratin 5 gene in DDD was not feasible.

A skin biopsy was performed from the cubital fossa area lesion over the arm and sent for histopathological investigation histopathology laboratory inpatient department complex to determine the diagnosis. A piece of 0.5 cm × 0.4 cm × 0.3 cm was extracted. The pathology laboratory received a tissue sample which was then treated with formalin, dehydrating chemicals, clarifying agent, and paraffin wax to make a block. The section was sliced using a microtome and a microscopic slide was made with hematoxylin and eosin staining. The histopathological examination reveals the histology of the skin, which includes an excessive thickening of the outer layer of the skin, thinning of the epidermis, increased pigmentation in the basal layer, focal elongation of the ridges in the lower layer of the skin with the formation of cysts filled with keratin, and a moderate inflammation in the superficial layer of the skin surrounding the blood vessels. A diagnosis of DDD was made based on the observed findings [Figure 2].

Figure 2 Photomicrograph of Dowling-Degos disease

The patient consulted at the dermatology department again with a histopathology report and he was counseled for pigmentary lesions. Symptomatic eczematous lesions over the body were treated with a mild potent topical corticosteroid.

Discussion

The Dowling-Degos sickness is thought to be caused by a mutation in the KRT5 gene. The KRT5 gene plays a crucial role in preserving the connection between keratinocytes, facilitating the transport of melanosomes into these cells, transferring organelles, and offering structural support to the nucleus. Due to the genetic abnormalities in this specific gene, individuals have hyperpigmented reticular macules on their bodies, particularly in the flexural locations. Genetic inheritance is the primary factor, although isolated occurrences can also be documented.[9] In our particular situation, there is a notable absence of family history, which is a contrasting characteristic compared to the typical scenario.

Variables can be seen in the age at which symptoms first appear. The majority of cases occur throughout the maturity or adolescent stage of the patient’s childhood. The presentation, on the other hand, dates back to childhood in our situation.[10]

The axillae, inguinal regions, face, neck, arms, and trunk are the areas most frequently afflicted. In some situations, individuals may have atrophic scars around the mouth, as well as comedone-like lesions on the face, neck, and trunk. In addition, epidermal and trichilemmal cysts may be present. However, these particular symptoms were not noticed in our patient. The histopathology of DDD reveals acanthosis, which is characterized by the downward extension of thin rete ridges. These ridges form reticulated patterns and exhibit a concentration of melanin at their tips. In addition, there may be occasional follicular plugging and the presence of horn cysts.[11]

Galli–Galli disease, Kitamura’s reticular acropigmentation, and Haber syndrome are other comparable diseases that can be mistaken for reticulate pigment disorder. Nevertheless, they can be distinguished from DDD by the presence of suprabasal dyskeratotic acantholysis, the hyperpigmented papules initially appear on the outer surfaces of acral areas, and the early lesions typically manifest as facial eruptions, respectively.[12]

Neurofibromatosis type 1 and acanthosis nigricans are two closely related conditions that can be easily confused with each other. Neurofibromatosis is characterized by the presence of many lesions in the inguinal and axillary regions. Histopathological examination reveals the morphology of neurofibroma. Acanthosis nigricans is characterized by the absence of reticular pigmentation.[13] DSH, DUH, and RAPK are all considered as different diagnoses for Dowling-Degos syndrome. The characteristics of it have been explained in the introduction section.

Conclusion

The case demonstrates DDD, an uncommon hereditary skin condition with distinct clinical and histological characteristics. Although there was no family history, the diagnosis was confirmed by doing a histopathology study, which revealed usual features that were consistent with DDD. The identification of this condition underscores the importance of considering rare dermatological entities in the differential diagnosis, particularly when clinical presentation aligns with established histopathological criteria. Further research and awareness are warranted to improve our understanding and management of this fascinating skin condition.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.
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