Confluent and reticulated papillomatosis (CARP), also known as Gougerot-Carteaud syndrome is a rare disorder first described by Gougerot and Carteaud in 1927 [1]. It occurs in all age groups, races, and genders. Usually, patients are asymptomatic. However, they may experience mild pruritus. The lesions are most commonly observed on the trunk [2]. Physical findings are limited to the skin.

CARP lesions begin as papules of 1 to 2 millimeters in diameters that are slightly hyperkeratotic to warty. They enlarge to form 4 to 5 millimeters lesions which coalesce and form confluent plaques centrally with a reticulated periphery. Skin markings are preserved, or in the neck and axillae, they may be exaggerated. It has been described as keratotic and vertically rippled plaques, and punctate pigmented papillomatosis [3] [4]. Rarely, atrophic macules may also be seen. A fine powdery scale is produced upon scraping of the lesions. Dermoscopy reveals an ill-defined brownish pigmentation, covered with white scales and a pattern labeled "sulci and gyri" [5]. The color of lesions in CARP are characterized by an early erythematous appearance that later evolves into a grayish brown color [6].

CARP lesions initially develop in the skin of epigastric or intermammary region, and over a period of weeks to months spread over the lower abdomen, breast, pubic area, and the flanks. Exceptions to this can occur, as in one case the lesions were confined to the cheeks and in another, they were confined to the pubic area [7] [8]. The mucous membranes are spared but the involvement of the face, proximal extremities, and forehead may be seen [9] [10].

• Pathologist

  Madhavi Naik, Consultant Pathologist, St Theresa's Hospital, Bengaluru, India. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References 1. Scheinfeld N. [ijpd.in]

• Developmental Delay

  The syndrome displays distinctive clinical findings represented by developmental delay, intellectual disability, epilepsy and autistic behaviour. Skin pigmentation has been observed in several cases (1). [medicaljournals.se]

• Pseudotumor

  Other oral therapies include clarithromycin, tetracycline, furacycline, azfuracycline, and cefdinir.3 Because of potential adverse reactions reported for minocycline, including pseudotumor cerebri, lupus-like syndrome, and autoimmune hepatitis, and the [healio.com]

• Epilepsy

  The syndrome displays distinctive clinical findings represented by developmental delay, intellectual disability, epilepsy and autistic behaviour. Skin pigmentation has been observed in several cases (1). [medicaljournals.se]

• Hematemesis

  March 1, 2018 A 49-year-old man presented to the emergency department with hematemesis and 2 episodes of melena. Examination findings included resting tachycardia and melenic stool. Blood pressure was 95/50 mm Hg. [consultant360.com]

• Hyperpigmentation

  We report three teenaged Caucasian patients with confluent and reticulated papillomatosis whose presentation was atypical due to the absence of hyperpigmentation and presence of a fine white scale. [ncbi.nlm.nih.gov]

  Thus, there is the possibility that the skin hyperpigmentation associated with 15q tetrasomy syndrome is being diagnosed as CRP. [medicaljournals.se]

  Histologic Features A basket-weave horn Papillomatosis of epidermis with deep depressions Thin epidermis and rete ridges Fusion of adjacent rete ridges forming X and Y configurations Slight hyperpigmentation of the basal layer [dxpath.com]

  […] papillomatosis Figure: 3 Confluent and reticulate papillomatosis Management Several antibiotics, especially minocycline and azithromycin, have been found to be effective when give for a period of 6-8 weeks Minocycline has occasionally been associated with hyperpigmentation [pcds.org.uk]

  The rash actually resolved within 2 weeks with only some residual post-inflammatory hyperpigmentation. [theketorash.com]

• Skin Disease

  Age range was 13-25 years and the skin disease had lasted for 6 months to 3 years. Initially, acanthosis nigricans was suspected in all cases as the skin histology was compatible with that diagnosis. [ncbi.nlm.nih.gov]

  Key Points *Rare *Affects the trunk area *Characterized by dark, scaly papules and plaques Confluent and reticulated papillomatosis of Gougerot and Carteaud, besides being a mouthful to say, is a relatively uncommon skin disease that usually affects young [ozarkderm.com]

  disease of unknown etiology characterized by flat papules taking a reticulated appearance. 2)History: Confluent and reticulated papillomatosis (CRP) was first described by Gougerot and Carteaud in 1927. [histopathology-india.net]

  Pediatric Service of Hospital Pedro Hispano Marlene Abreu Pediatric Service of Hospital Pedro Hispano Mariana Matos Martins Pediatric Service of Hospital Pedro Hispano Marta Teixeira Dermatology Service of Hospital Pedro Hispano Keywords: adolescence, skin [revistas.rcaap.pt]

• Follicular Plugging

  Clinically, one case had an atypical clinical presentation, and microscopically follicular plugging was seen in the majority of cases. [ncbi.nlm.nih.gov]

• Hypopigmented Macule

  Initially started as hypopigmented macules on the chest at the age of 3 years and slowly progressed to involve the entire chest, lower abdomen, and back. [ijpd.in]

• Seizure

  He had experienced frequent generalized seizures since 8 years of age, which were treated with clobazam and carbamazepine. [medicaljournals.se]

• Generalized Seizure

  He had experienced frequent generalized seizures since 8 years of age, which were treated with clobazam and carbamazepine. [medicaljournals.se]

• Hyperactivity

  […] hypopigmented lesions in dark skin individuals or as persistently erythematous lesions in white skin individuals. 7,11 The exact etiology of CARP remains unknown, but several hypotheses have been developed to explain the abnormal process of keratinization and hyperactive [consultant360.com]

The diagnostic criteria for CARP is proposed as:

1. Scaly brown macules and patches. Some appearing papillomatous and reticulated.
2. Involvement of the neck, upper trunk, or flexural areas.
3. No response to antifungal therapy, or negative fungal staining.
4. A favorable response to antibiotics.

On potassium hydroxide (KOH) test, pityrosporum ovale or pityrosporum orbiculare spores and rarely hyphae may be found. A fungal culture may also reveal these microorganisms in some cases. On wood lamp examination, yellow fluorescence can occur if pityrosporum organisms are present. Electron microscopy can help detect alterations in the structure and arrangement of cornified cells in some lesions. An increase may be observed in transitional cell layer, the number of melanosomes in the stratum corneum, and the number of lamellar bodies in the stratum granulosum [11]. On immunohistochemical analysis, suprabasal keratin 16 expression and an intense focal staining in the stratum granulosum are revealed, with an increased number of epidermal cells with Ki-67 binding in the stratum malpighii.

Histopathological features of CARP include:

1. Basket-weave hyperkeratosis.
2. Papillomatosis.
3. Focal acanthosis (limited to areas of rete pegs elongation).
4. Raised basal melanin pigmentation.

1. Gougerot H, Carteaud A. Papillomatose pigmentée innominée. Bull Soc Fr Dermatol Syphil. 1927;34(Nov 10):719-721.
2. Tamraz H, Raffoul M, Kurban M, Kibbi AG, Abbas O. Confluent and reticulated papillomatosis: clinical and histopathological study of 10 cases from Lebanon. J Eur Acad Dermatol Venereol. 2013;27(1):e119-23.
3. Min ZS, Tan C, Xu P, Zhu WY. Confluent and reticulated papillomatosis manifested as vertically rippled and keratotic plaques. Postepy Dermatol Alergol. 2014;31(5):335-7.
4. Ibekwe PU, Ukonu BA. Punctate, pigmented, and verrucous papillomatosis: a rare variant of Gougerot-Carteaud syndrome. Int J Dermatol. 2016;55(7):806-808. doi: 10.1111/ijd.13097.
5. Bernardes Filho F, Quaresma MV, Rezende FC, Kac BK, Nery JA, Azulay-Abulafia L. Confluent and reticulate papillomatosis of Gougerot-Carteaud and obesity: dermoscopic findings. An Bras Dermatol. 2014;89(3):507-9.
6. Bhagwat PV, Tophakhane RS, Shashikumar BM, Noronha TM, Naidu V. Three cases of Dowling Degos disease in two families. Indian J Dermatol Venereol Leprol. 2009;75(4):398-400.
7. Faergemann J, Fredriksson T, Nathorst-Windahl G. One case of confluent and reticulate papillomatosis (Gougerot-Carteaud). Acta Derm Venereol. 1980;60(3):269-71.
8. Broberg A, Faergemann J. A case of confluent and reticulate papillomatosis (Gougerot-Carteaud) with an unusual location. Acta Derm Venereol. 1988;68(2):158-60.
9. Lee D, Cho KJ, Hong SK, Seo JK, Hwang SW, Sung HS. Two cases of confluent and reticulated papillomatosis with an unusual location. Acta Derm Venereol. 2009;89(1):84-5.
10. Kim BS, Lim HJ, Kim HY, et al. Case of minocycline-effective confluent and reticulated papillomatosis with unusual location on forehead. J Dermatol. 2009;36(4):251-3.
11. Jimbow M, Talpash O, Jimbow K. Confluent and reticulated papillomatosis: clinical, light and electron microscopic studies. Int J Dermatol. 1992;31(7):480-3.