1. Dowling-Degos Disease

2. Classification of Reticulate Dermatoses
Vascular
Cutis marmorata
Cutis marmorata telangiectatica congenita (CMTC)
Livedo reticularis (LR)
Livedo racemosa
Livedoid vasculopathy
Reticulate purpura
Pigmentary
Dowling-Degos disease (DDD)
Galli-Galli disease
Dermatopathia pigmentosa reticularis
Dyschromatosis universalis hereditaria (DUH)
Reticulate acropigmentation
Reticulate acropigmentation of Dohi
Reticulate acropigmentation of Kitamura
Syndromes associated with reticulate pigmentation
Naegeli-Franceschetti-Jadassohn syndrome
Mendes da Costa-van der Valk syndrome
Hoyeraal-Hreidarrson syndrome
Partington syndrome
Atopic dirty neck
Epidermolysis bullosa with mottled pigmentation
Systemic sclerosis

3. Classification of Reticulate Dermatoses :Continue
Poikilodermatous
Inherited
 Rothmund-Thomson syndrome More Details
Dyskeratosis congenita
Xeroderma pigmentosum
Cockayne syndrome
Fanconi anemia
Mendes da Costa syndrome
Kindler syndrome
Degos-Touraine syndrome
Hereditary sclerosing poikiloderma of Weary
Hereditary acrokeratotic poikiloderma of Weary
Werner's syndrome (adult progeria)
Chanarin-Dorfman syndrome
Diffuse and macular atrophic dermatosis
Acquired
Poikiloderma of Civatte
Injury by cold, heat, or ionizing radiation
Chronic graft-versus-host disease (cGVHD)
Others
Dermatomyositis
Lupus erythematosus
Parapsoriasis
Mycosis fungoides
Poikiloderma-like cutaneous amyloidosis

4. Classification of Reticulate Dermatoses: Continue
Infectious
Confluent and reticulate papillomatosis (CRP)
Erythema infectiosum
Erythema marginatum (EM)
Congenital rubella syndrome
Metabolic
Macular amyloidosis
Amyloidosis cutis dyschromica
Reticular erythematous mucinosis
Hunter's syndrome
Others
Erythema ab igne
Prurigo pigmentosa
Mucosal lichen planus
Leukoplakia
Neonatal lupus erythematosus (LE)
Hereditary angioedema
Extensive congenital erosions and vesicles healing with reticulate scarring
Atrophodermia vermiculata
Nekam's disease

5. Dowling-Degos Disease
DDD is a late-onset genodermatosis, occurring usually in adulthood, with the appearance of hyperpigmented macules. The onset of the disease - a rare genodermatosis of autosomal dominant transmission with variable penetrance - usually occurs in the third or fourth decade of life. It is also referred to as 'Dark Dot Disease'.  It affects predominantly women in a ratio of 2:1 and has no race predilection.
The pigmentation gradually increases over time. The disease initially affects the armpits and groin and later the intergluteal, inframammary regions and the neck and trunk. Pruritus in the folds may be reported. Over time comedo-like lesions also appear on the back and neck, and perioral cribriform scars and follicular cysts. The disease has been associated with Hidradenitis Suppurativa (HS), also known as 'Acne Inversa', and multiple keratoacanthomas, perhaps because DDD causes a defect in the pilo sebaceous epithelial proliferation.  .

6. Dowling-Degos Disease
The disease is characterized by acquired reticulated skin hyperpigmentation, which begins in the armpits, groin and later spreads to other skin folds. It can affect (although more uncommonly), the wrist, the antecubital and popliteal space, the face, scalp, scrotum and vulva .  Some patients complain of itching in the macula. These lesions do not change with sun exposure. Comedo-type black lesions on the face, back and in the same areas described above can also be observed , as well as cribriform scars and perioral acne in patients with no history of acne. Other features may be present such as mental retardation and pilar cyst.  While at the benign stage the disease shows no inflammatory phenomena, it is nevertheless very unsightly

7. (b) Close-up of the left axilla.
Dowling-Degos Disease with Asymmetrical Axillary Distribution and No KRT 5 Exon 1 Mutation Acta Dermato0venereologica, 2OO7
a) Multiple, small brown macules and papules in reticular distribution localized on the axilla. The lesion on the left side was more pronounced than that on the right.
(b) Close-up of the left axilla.
. Histopathological picture showing irregular elongation of rete ridges and basal pigmentation 

8. Dowling-Degos Disease involving the vulva and back Dermatology Online Journal 17 (7): 1 

9.   Dowling-Degos Disease involving the vulva and back Vulvar biopsy: The epidermis shows thin elongated, branching rete ridges that contain dense pigmentation in the lower one third. Scattered melanophages are present in the upper dermis. There is mild hyperkeratosis overlying the epidermis. Dermatology Online Journal 17 (7): 1 

10. Dowling-Degos Disease involving the vulva and back The histology is distinctive with marked, heavily pigmented, slender, and often branched, elongation of the rete ridges Perianal biopsy: A small keratin cyst is present within one of the rete ridges Dermatology Online Journal 17 (7): 1 

11. Dowling-Degos Disease
 It is also known as ‘pigmented reticulate anomaly of the flexures’. It is important to distinguish this from acanthosis nigricans, which can be a skin sign of internal diseases.
There are a number of probable variants of Dowling-Degos disease:
Localised Dowling-Degos
Generalised Dowling-Degos
Galli-Galli disease
Reticulate acropigmentation of Kitamura
Haber disease
Symmetrical acropigmentation of Dohi
In a few cases, pigmentation is absent. What are the clinical features of Dowling-Degos disease?
Dowling-Degos disease affects only the skin and there are no internal effects. Skin affected by Dowling-Degos disease can be itchy, especially in summer when the effects of heat, perspiration and friction aggravate the pigmentation and itch. Blistering is not a feature of this disease.
Five patterns of classic Dowling-Degos and Galli-Galli disease are described.
1. Increased pigmentation
Freckle-like pigmentation usually first appears in early adult life in the great folds of the skin such as armpits, groin, between and under the breasts. Common sites also include the upper arms, upper inner thighs, behind the knees and neck. It may be localized to one area such as the genitalia (scrotum or vulva) (localized Dowling-Degos disease) or gradually extend to affect most of the skin surface (generalized Dowling-Degos disease). The pigmentation may worsen in pregnancy and with sun exposure.
A number of patterns have been described:
Dappled or reticulate patterns
‘Dark spots’ – small black dots centered on hair follicles
Flat spots (macules) or slightly raised small spots (papules)
Varying shades of brown or black.
2. Follicular papules
These are small raised scaly pigmented or non-pigmented spots based on hair follicles

12. Dowling-Degos Disease
3. Reduced pigmentation
These are small flat spots (macular) or raised (papular) spots that are paler than the normal skin.
4. Comedones
These are blackhead-like spots most often found on the neck.
5. Scars
These are pitted acne-like scars most often occurring on the chin.
Associated disorders with Dowling-Degos disease
@ Hidradenitis suppurativa has been reported in association with Dowling-Degos disease more often than would be expected by chance. Thus patients with Dowling-Degos disease are more likely to also have hidradenitis suppurativa.
Other conditions of uncertain relevance have been rarely reported in association with classic Dowling-Degos disease:
@ Squamous cell carcinomas and keratoacanthomas
Abnormalities of skin appendages such as nail dystrophy and absence of vellus hair.
@ Seborrhoeic keratoses
@ Epidermoid or trichilemmal cysts .
Diagnosis of Dowling-Degos disease
The diagnosis is made on the clinical features and confirmed on skin biopsy.
There are two histological (pathological) variants:
Classic Dowling-Degos disease – the epidermis shows elongated branched (antler-like) rete ridges with increased melanin pigmentation at the tips. There is no increase in melanocyte number.
Galli-Galli disease – in addition to the above features, there is also acantholysis (separated skin cells) with overlying parakeratosis (horny layer cells retaining their nuclei

13. Dowling-Degos Disease I.J.Derm. : 2014 : 59 : 1 : 3

14. Dowling-Degos Disease

15. Dowling-Degos Disease
perioral pitting scars hyperpigmentation genitalia 

16. Pathology Dowling Degos dermatoscopie

17. Dowling-Degos Disease
A) The epidermal down growths showed a misinform or antler-like pattern with irregular elongation of the rete ridges in the lesion (H&E, ×100).
(B) There is increased melanin pigment at the tips of the epidermis (H&E, ×200).
(C) There is increased pigmentation of the rete ridges on Fontana-Masson staining (Fontana-Masson, ×200).
(D) Compared with perilesional normal skin, the S100 protein staining reveals no increase in the number of melanocytes (S100 protein, ×200).

18. Dowling-Degos Disease
Histopathological findings of DDD include moderate orthokeratosis or hyperkeratosis, thinning of the suprapapillary epithelium and elongation of the papillae with basal layer hyperpigmentation. These threadlike growths of the epidermis have the appearance of "antlers" and generally involve the follicle with a follicular plug. A perivascular lymphohistiocytic infiltrate in the papillary dermis and pseudo-horny cysts can also be observed. Staining for S100 does not generally show increased numbers of melanocytes, suggesting that the pigment does not arise from increased density of melanocytes.  

19. Dowling-Degos Disease

20. The characteristic reticulate appearance of Dowling Degos disease

21. Dowling-Degos Disease

22. Dowling-Degos Disease
acantholytic form of Dowling-Degos disease (DDD) in skin biopsy specimens from axilla.
A , Typical histologic features of DDD characterized by downward elongations of rete ridges with reticulated or fenestrated pattern and occasional horn cysts. Suprabasal acantholysis is present at margin.
B , Higher power view of suprabasal acantholysis.
C , Lacunae or clefts in suprabasal areas.
D , Intracellular edema (spongiosis) of upper epidermis. 

23. Dowling-Degos Disease

24. Dowling-Degos disease and hidradenitis suppurativa: Co occurrence or association? I Derm. Online J.2013 : 4 : 3: 191
@ Multiple nodules and plaques with sinuses discharging pus involving the buttocks
@ Nodules, plaques and scars involving the inner aspect of the upper thigh and anogenital region

25. Dowling-Degos disease and hidradenitis suppurativa: Co occurrence or association? I Derm. Online J.2013 : 4 : 3: 191
@ Crusted plaque over the right leg @ Multiple dark brown pigmented macules and comedo like lesions (dark dot follicle) involving the right axilla

26. Dowling-Degos disease and hidradenitis suppurativa: Co occurrence or association? I Derm. Online J.2013 : 4 : 3: 191
@ Multiple dark brown pigmented macules and comedo (dark dot follicle) involving the left Scattered comedo-like lesions (dark dot follicles) involving the right Multiple discrete pitted scars over the face

27. Dowling-Degos disease and hidradenitis suppurativa: Co occurrence or association? I Derm. Online J.2013 : 4 : 3: 191
@ Neutrophilic and histiocytic infiltration around the pilosebaceous apocrine units @ Irregular epidermis, acanthosis and elongation of rete ridges with increased basal melanin pigmentation

28. Dowling-Degos disease
@ Areas of hyperplasia and microcystic transformation of the sweat glands
@ Areas of cystic transformation of the sweat glands

29. Dowling-Degos disease and malignant melanoma: Association I J D V L ,2015 : 81 : 6 : 627
A] Multiple grouped shiny skin-colored to erythematous nodules and plaques on the left side of the scrotum with adjacent papules and nodules.
b) Face showing discrete, hyperpigmented macules on the forehead. Pitted scars prominent on the nose, perinasal and perioral regions.
(c) Brown hyperpigmented macules in the right axilla

30. Dowling-Degos disease and malignant melanoma: Association I J D V L ,2015 : 81 : 6 : 627
 (a) Nests of tumor cells having pleomorphic vesicular nuclei, prominent eosinophilic nucleoli and moderate amount of cytoplasm (H and E stain, ×400), (b) HMB-45 monoclonal antibody staining the cytoplasm of the tumor cells (×100)
 Elongation and branching of rete pegs with basal hyperpigmentation, consistent with Dowling-Degos disease
                                                                                                                          

31. Dowling-Degos disease
Hyperkeratosis, acanthosis and papillomatosis with scant perivascular lymphocytic infiltration was observed in the lesional skin (

32. Dowling-Degos Disease
Some authors refer to Acropigmentation of Kitamura, and Galli-Galli disease as differential diagnoses of DDD. 
@Reticulate Acropigmentation of Kitamura (RAPK) is a sporadic autosomal dominant disease of unknown origin. It prevails in Japan, but has been observed worldwide. Its clinical features consist of hyperpigmented atrophic macules on the backs of the hands and feet. Its onset is in childhood. The lesions darken with time and worsen with sun exposure. Pitting on the palms and soles and dorsa of the fingers can also be found. . 
@Galli-Galli disease is an acantholytic variant of Dowling-Degos disease which presents in people aged between 15 and 5o While the mechanism of acantholysis is unknown authors have suggested that it results from of loss of epidermal cell stability due to a keratin 5 defect. Clinical symptoms include the presence of hyperpigmentation of the flexures together with itching, and sometimes with erythematous, scaly papules on these sites as well as on the trunk and proximal extremities. The histopathology resembles that of DDD, but with foci of acantholysis. Another differential diagnosis with Galli-Galli disease would be epidermolysis bullosa with mottled pigmentation, although this disease has other additional features such as blisters and palmoplantar hyperkeratosis. Treatment usually consists of topical steroids and retinoids, with little success. 
@DDD must also be differentiated from acanthosis nigricans which also shows a predilection for skin folds, but with the emergence of velvety plaques. Histopathologically the papillae are less elongated and without follicular involvement. Patients with neurofibromatosis may also have freckle-like (ephelides) lesions in the armpits, but this disease is easily distinguished from DDD. 
No other complementary examination exists to aid diagnosis of DDD apart from a typical histopathologic examination associated with compatible clinical features, as we did in this case

33. Dowling-Degos Disease
A variety of treatments can be tried but with unsatisfactory outcomes: topical hydroquinone, tretinoin, adapalene and corticosteroids, as well as Er:YAG lasers. Isotretinoin would be an option since it produces an alteration in the pattern of keratinization, 20mg/day of oral and topical isotretinoin.

34. Reticulate acropigmentation of Kitamura Dermatology Online Journal 14 (8): 7
RAPK was first described in Japan: about 100 cases have been reported, mostly in Asian ethnic groups. The characteristic presentation of RAPK is as pigmented, angulated, irregular freckle-like lesions with atrophy on the surface, arranged in a reticular pattern on the dorsa of the hands and feet. The lesions usually start in the first and second decades of life and gradually extend onto the extremities and rarely on the face and eyelids. The lesions usually slowly darken over time . Sunlight may aggrevate the condition. Pits and breaks in the dermatoglyphics are found on the palms, soles and dorsal phalangeal surfaces .
Histopathological examination classically shows epidermal atrophy associated with club-like elongation of the rete ridges and an excess of melanin in the basal layer .
The differential diagnosis of RAPK include diseases presenting with reticulated or punctate hyperpigmentation like dyskeratosis congenita, dyschromatosis universalis herediteria, Franceschetti-Jadassohn's syndrome, dermatopathia pigmentosa reticularis, acropigmentation of Dohi (RAD) and Dowling-Degos Disease (DDD) . RAD is also an acral type of dyschromatosis (dyschromatosis symmetrica herediteria) that usually starts in infancy or early childhood as hypopigmented and hyperpigmented macules over the dorsa of the hands and feet. The differentiation between RAD and RAPK is based on clinical and histological findings. In RAPK there are usually no hypopigmented macules and histologically there is epidermal atrophy and increase in the number of basal melanocytes. DDD is also an autosomal dominant pigmented skin disorder characterized by reticular hyperpigmentation on flexor areas such as the neck, axilla, antecubital fossa, submammary area and groin. Dark comedo-like lesions and pitted perioral acneiform scars may be present. Rarely hypopigmented macules or papules are observed. Histologically there are pigmented filiform epidermal projections involving the follicular infundibulum as well as the epidermis

35. Variants of Dowling-Degos disease
There have been a number of case reports describing patients with overlapping features between classic Dowling-Degos disease and the following conditions, but these are now thought to be variants of Dowling-Degos disease.
@ Kitamura reticulate acropigmentation
Kitamura reticulate acropigmentation tends to first appear in childhood or adolescence as:
Dark freckled pigmentation on the backs of the hands and tops of feet
Palmar pits
Discontinuity of the fingerprint lines
Epidermoid cysts
Flat (macular) or raised (papular) spots with reduced or absent pigment
@ Gali & Gali disease
Acantholytic variant of Dowling Degos disease .Galli-Galli disease is a benign but very pruritic and unaesthetic genodermatosis. Its mode of inheritance is believed to be autosomal dominant with variable penetrance, but it can occur sporadically , as in our patient. As with DDD it is believed to be linked to mutations in the KRT5 gene . Clinically it is characterized by reticulated hyperpigmentation predominantly affecting the flexures along with pruritic, erythematous, scaly papules, similar to the DDD. Histopathologic examination reveals digitiform elongation of the rete ridges seen in DDD, together with suprabasal focal acantholysis  .
@ Symmetrical acropigmentation of Dohi
Symmetrical acropigmentation of Dohi starts to appear in infancy or early childhood as pinpoint to pea sized flat (macular) spots of increased and decreased pigmentation on the backs of the hands.

36. Galli-Galli Disease: A Rare Acantholytic Variant of Dowling-Degos Disease Case Reports in Medicine Volume 2011 (2011)
Galli-Galli disease (GGD) is a very rare variant of the Dowling-Degos disease (DDD) with the histologic finding of focal acantholysis.
Photo: A, B

37. Galli-Galli Disease: A Rare Acantholytic Variant of Dowling-Degos Disease Case Reports in Medicine Volume 2011 (2011)
Hematoxylin and eosin. (a) Discrete hyperkeratosis, elongated rete ridges with digitiform projections, and focal acantholysis with formation of linear clefts. Presence of mixed dermal inflammatory infiltrate.
(b) Dyskeratotic cells in the interior of a acantholytic cleft. (c) and (d) Digitiform elongation of the rete ridges, with hyperpigmentation of the basal layer confined to the tips of the rete ridges. Suprabasal
Photo: C, D

38. Reticulate acropigmentation of Kitamura Dermatology Online Journal 14 (8): 7

39. Reticulate acropigmentation of Kitamura Dermatology Online Journal 14 (8): 7

40. Presentation of Reticulate Acropigmentation of Kitamura and Dowling-Degos Disease Overlap J Clin Aesthet Dermatol ; 5(5): 41.

41. Presentation of Reticulate Acropigmentation of Kitamura and Dowling-Degos Disease Overlap J Clin Aesthet Dermatol ; 5(5): 41.

42.  A case of reticulate acropigmentation of Kitamura: Dowling Degos disease overlap with unusual clinical manifestations I L Derm2014   : 59 : 3   : Reticulate hyperpigmentation on: (a) Dorsa of both hands (b) Dorsa of both feet (c) Neck (d) Axilla

43.   A case of reticulate acropigmentation of Kitamura: Dowling Degos disease overlap with unusual clinical manifestations I L Derm2014   : 59 : 3   : Unusual features: (a) Reticulate hyperpigmentation in periorbital area (b) Reticulate hyperpigmentation on scrotum (c) Hypopigmented macules on trunk (d) Acneiform scars on nose

44. A case of reticulate acropigmentation of Kitamura: Dowling Degos disease overlap with unusual clinical manifestations I L Derm2014   : 59 : 3   : 290-
Histopathology of skin lesions: (a) Biopsy from axillary lesion demonstrating filiform elongation of the rete ridges, hyperpigmentation of basilar keratinocytes, and clusters of melanocytes at the tip of the rete ridges along with follicular plugging (H and E, ×10) (b) High-power view of the same (H and E, ×40) (c) Melan-A staining demonstrating the increased melanocytes (×40) (d) Biopsy from hypopigmented macules showing reduced number of melanocytes (H and E, ×40)

45. Differential diagnosis of DDD, RAK, HS and RAD DDD: Dowling-Degos disease, RAK: reticulate acropigmentation of Kitamura, HS: Haber's syndrome, RAD: reticulate acropigmentation of Dohi, AD: autosomal dominant, AR: autosomal recessive.

46. Dermatopathia pigmentosa reticularis I. Drm. Online J
Reticulate pigmentation on the trunk Diffuse nonscarring alopecia

47. Dermatopathia pigmentosa reticularis I. Drm. Online J
Onychodystrophy of finger nails Plantar hyperkeratosis

48. Dermatopathia pigmentosa reticularis I. Drm. Online J
Histopathology; showing melanophages and absence of skin adenexa

49. Reticulate Acropigmentation of Dohi Indian J Dermatol. 2012 ; 57(1): 42
Reticulate acropigmentation of Dohi also called dyschromatosis symmetrica hereditaria or symmetrical dyschromatosis of the extremities is an autosomal dominant inherited disorder. It is characterized by mottled pigmentation with patchy depigmentation commonly over the back of the hands and feet and sometimes on the arms and legs
Hyperpigmented and hypopigmented macules over dorsum of hands
Hyperpigmented macules over both palms

50. Reticulate Acropigmentation of Dohi Indian J Dermatol. 2012 ; 57(1): 42
Freckle like macules over face
,, ,, , Mottled pigmentation over buttocks

51. Reticulate Acropigmentation of Dohi Indian J Dermatol. 2012 ; 57(1): 42
Biopsy from hyperpigmented macule showing abundance of melanocytes in basal layer and the presence of melanocytes in other epidermal layers
, , , Biopsy from hypopigmented macule showing relatively less melancyte

52. Reticulate Acropigmentation of Dohi