Collection of dermatological disorders

Last updated: April 27, 2023

Epidermoid cysttoggle arrow icon

  • Definition: encapsulated lesion containing keratin and lipids and lined with stratified squamous epithelium
  • Epidemiology: most common cutaneous cyst
  • Clinical features
    • Slow-growing, nontender skin-colored nodule
      • Dome-shaped, firm, mobile
      • A dark-colored punctum may be seen.
      • Does not dimple when pinched
    • Located predominantly on the face, head, neck, trunk, and/or genitals
    • Inflammation and spontaneous rupture may occur.
    • Infection causes a painful, erythematous mass that may exude pus.
    • High probability of recurrence
  • Differential diagnosis: trichilemmal cyst (pilar cyst)
  • Treatment
    • Asymptomatic cysts do not require treatment.
    • Definitive treatment (usually for cosmetic reasons): surgical excision
    • May resolve spontaneously when ruptured
    • Oral antibiotics, incision, and drainage for infected cysts
    • Intralesional steroids (e.g., triamcinolone) may help reduce inflammation.

Cat scratch diseasetoggle arrow icon


Cutaneous mastocytosis (urticaria pigmentosa)toggle arrow icon

Miliariatoggle arrow icon

Types of miliaria
Miliaria crystallina Miliaria rubra Miliaria profunda
  • Most common type
  • Usually seen in adult men in tropical climates, who have had repeated episodes of miliaria rubra
Level of sweat duct blockage
Clinical features
  • Clear 1–2 mm vesicles with no erythema

Nummular eczema (nummular dermatitis)toggle arrow icon

Gianotti-Crosti syndrometoggle arrow icon

Angiokeratomatoggle arrow icon

Dyshidrotic eczematoggle arrow icon

Erythema ab ignetoggle arrow icon

  • Description: reticular erythema with telangiectasias
  • Etiology: paralysis of the deep vascular plexus of the skin caused due to chronic heat application (e.g., infrared radiation, hot water bottles)
  • Pathophysiology: direct skin application of heat for extended periods of time → direct heat triggers increased melanin production → marbled, brownish hyperpigmentation
  • Treatment [12]
  • Complications [12]

Callus/Clavustoggle arrow icon

  • Callus: thick, toughened skin caused by repeated mechanical pressure and friction
  • Clavus: a painful, hyperkeratotic lesion with a center core (corn) caused by frictional forces and trauma

Pitted keratolysis (keratoma plantare sulcatum)toggle arrow icon

Localized lipodystrophytoggle arrow icon

Perioral dermatitis (stewardess disease)toggle arrow icon

  • Description: chronic facial dermatitis affecting the perioral region
  • Epidemiology: primarily children and women 20–45 years of age [14]
  • Etiology
    • Unknown
    • Presumably caused by regular application of (glucocorticoid) creams and/or cosmetics
  • Clinical features
    • Erythema with grouped papules and pustules
    • Dry skin with painful burning and a sensation of tightness
    • No residual scarring after resolution
  • Treatment

SAPHO syndrometoggle arrow icon

Livedo reticularistoggle arrow icon

Types of livedo reticularis [15]
Physiological livedo (idiopathic livedo) Pathological livedo (livedo racemosa)
  • A vascular syndrome that can be caused by either benign autonomic dysregulation of cutaneous perfusion or pathological obstruction of blood vessels
  • Autonomic dysregulation (functional disturbance) causing slowed cutaneous perfusion in response to external factors (i.e., cold)
  • Localized obstructions slow the blood flow (organic disturbance)
Clinical features
  • Symmetrical livedo reticularis (regular, small, round) of the extremities and sometimes the trunk
  • Triggered by cold, regresses after application of warmth
  • Warmth, sauna, alternating cold and warm baths
  • Treat the underlying disease
  • Improves with age
  • Depends on the underlying disease (usually more difficult to treat)

Livedo reticularis that does not regress after application of warmth is indicative of an underlying vascular disease and requires treatment.

Xeroderma pigmentosumtoggle arrow icon

Pseudofolliculitis barbaetoggle arrow icon

  • Description: inflammatory skin reaction in response to short hair that becomes entrapped within the skin
  • Etiology
    • Usually occurs due to shaving (also known as razor bumps)
    • Most common in African American men because the hair shafts typically form tight coils
  • Pathophysiology
    • Extrafollicular penetration: Hair enters the interfollicular epidermis after it exits the follicular orifice.
    • Transfollicular penetration: Hair penetrates the dermis before exiting the follicular orifice.
  • Clinical features
  • Diagnostics: a clinical diagnosis
  • Treatment
  • Complications

Albinismtoggle arrow icon

Waardenburg syndrometoggle arrow icon

Angiosarcomatoggle arrow icon

  • Definition: a rare, very aggressive vascular malignancy, arising from endothelial cells of blood or lymphatic vessels [19]
  • Epidemiology: peak incidence age > 70 years [19]
  • Etiology [19]
  • Clinical features [20][21]
    • Location
      • More common in sun-exposed areas
      • Usually occur on the head, neck, and breast
      • May involve the internal organs (e.g., hepatic angiosarcoma)
    • Lesion
      • Blue/purple-colored with a bruise-like appearance
      • Later stage: hemorrhage or ulceration
      • High variability in appearance
  • Treatment [21]
    • Complete resection with wide margins
    • Resection may be complicated by the aggressive course of the disease and delayed diagnosis.

Tattoo-associated skin reactionstoggle arrow icon

Hyperhidrosistoggle arrow icon

Embolia cutis medicamentosatoggle arrow icon

Sebaceous hyperplasiatoggle arrow icon

Cutaneous granulomastoggle arrow icon

Cutaneous granulomas are a group of conditions characterized by a chronic inflammatory skin response to a variety of stimuli, including metabolites, foreign bodies, and infection. They are classified as infectious or noninfectious. Diagnosis is primarily clinical For more information on the etiology, pathophysiology, and pathology of these conditions, see “Granulomatous inflammation.” [29]

Noninfectious cutaneous granulomas

Noninfectious cutaneous granulomas are often manifestations of systemic diseases, including diabetes, rheumatoid arthritis, and sarcoidosis.

Granuloma annulare

Necrobiosis lipoidica [33]

Rheumatoid nodules

  • Definition: inflammatory cutaneous or subcutaneous lesions found primarily at pressure points (e.g., extensor side of the forearm, bony prominences)
  • Epidemiology [34]
  • Clinical features: nontender, firm, subcutaneous nodules
  • Histopathology: central necrosis with surrounding palisading histiocytes and granulomatous tissue [34]
  • Treatment: intralesional corticosteroid injection or excision only required if the nodule causes pain or impairs movement
  • For more information, see “Rheumatoid arthritis.”

Lupus pernio

Foreign body granulomas

Infectious cutaneous granulomas

Keratosis pilaristoggle arrow icon

  • Definition: a benign skin condition caused by the build-up of keratin around the hair follicles
  • Epidemiology: : typically affects children or adolescents
  • Etiology
  • Pathophysiology: increased keratinization keratin plug formation at follicle orifices
  • Clinical features
    • Asymptomatic lesions
    • Keratotic follicular papules; (the papules are hard, resulting in a rough skin texture)
    • Perifollicular erythema may be seen.
    • Most commonly located on the extensors of the proximal arms and thighs (less commonly on the face, trunk, buttocks, and distal extremities)
    • Exacerbation during the winter months and during pregnancy is common. [40][41]
  • Diagnosis: clinical
  • Treatment
  • Prognosis: benign condition [40]

Referencestoggle arrow icon

  1. Lee HE, Yang CH, Chen CH, Hong HS, Kuan YZ. Comparison of the Surgical Outcomes of Punch Incision and Elliptical Excision in Treating Epidermal Inclusion Cysts: A Prospective, Randomized Study. Dermatologic Surgery. 2006; 32 (4): p.520-525.doi: 10.1111/j.1524-4725.2006.32105.x . | Open in Read by QxMD
  2. Zuber TJ. Minimal excision technique for epidermoid (sebaceous) cysts.. Am Fam Physician. 2002; 65 (7): p.1409-12, 1417-8, 1420.
  3. Opavsky MA. Cat scratch disease: The story continues.. The Canadian journal of infectious diseases = Journal canadien des maladies infectieuses. 1997; 8 (1): p.43-9.doi: 10.1155/1997/982908 . | Open in Read by QxMD
  4. Berzigotti A, Magalotti D, Zappoli P, Rossi C, Callea F, Zoli M. Peliosis hepatis as an early histological finding in idiopathic portal hypertension: A case report.. World journal of gastroenterology. 2006; 12 (22): p.3612-5.doi: 10.3748/wjg.v12.i22.3612 . | Open in Read by QxMD
  5. Atila K, Coker A, Uçar D, et al. A rare clinical entity misdiagnosed as a tumor: peliosis hepatis.. Ulusal travma ve acil cerrahi dergisi = Turkish journal of trauma & emergency surgery : TJTES. 2007; 13 (2): p.149-53.
  6. Bleibel W, Curry MP. Peliosis Hepatis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. Last updated: June 27, 2017. Accessed: September 14, 2017.
  7. Hepatic Peliosis. Updated: September 14, 2017. Accessed: September 14, 2017.
  8. Wenzel FG, Horn TD. Nonneoplastic disorders of the eccrine glands.. J Am Acad Dermatol. 1998; 38 (1): p.1-17; quiz 18-20.doi: 10.1016/s0190-9622(98)70532-8 . | Open in Read by QxMD
  9. Fernández-Crehuet P, Ruiz-Villaverde R. Pitted keratolysis: an infective cause of foot odour.. CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne. 2015; 187 (7): p.519.doi: 10.1503/cmaj.140809 . | Open in Read by QxMD
  10. Taïeb A, Plantin P, Du Pasquier P, Guillet G, Maleville J. Gianotti-Crosti syndrome: a study of 26 cases.. Br J Dermatol. 1986; 115 (1): p.49-59.doi: 10.1111/j.1365-2133.1986.tb06219.x . | Open in Read by QxMD
  11. Chuh A, Lee A, Zawar V. The diagnostic criteria of Gianotti-Crosti syndrome: are they applicable to children in India?. Pediatr Dermatol. ; 21 (5): p.542-7.doi: 10.1111/j.0736-8046.2004.21503.x . | Open in Read by QxMD
  12. Wiechers T, Rabenhorst A, Schick T, et al. Large maculopapular cutaneous lesions are associated with favorable outcome in childhood-onset mastocytosis.. J Allergy Clin Immunol. 2015; 136 (6): p.1581-1590.e3.doi: 10.1016/j.jaci.2015.05.034 . | Open in Read by QxMD
  13. Tolaymat L, Hall MR. Perioral Dermatitis. StatPearls. 2020.
  14. Iacobelli J, Harvey NT, Wood BA. Sebaceous lesions of the skin. Pathology. 2017; 49 (7): p.688-697.doi: 10.1016/j.pathol.2017.08.012 . | Open in Read by QxMD
  15. Bryden AM, Dawe RS, Fleming C. Dermatoscopic features of benign sebaceous proliferation. Clin Exp Dermatol. 2004; 29 (6): p.676-677.doi: 10.1111/j.1365-2230.2004.1612.x . | Open in Read by QxMD
  16. Vlahova L, Kretschmer L, Schön MP, Mössner R. Embolia Cutis Medicamentosa after Subcutaneous Injection with Glatiramer Acetate. Case Reports in Dermatology. 2021; 13 (1): p.114-120.doi: 10.1159/000510017 . | Open in Read by QxMD
  17. Tabor D, Bertram CG, Williams AJK, Mathers ME, Biswas A. Nicolau Syndrome (Embolia Cutis Medicamentosa): A Rare and Poorly Recognized Iatrogenic Cause of Cutaneous Thrombotic Vasculopathy. Am J Dermatopathol. 2018; 40 (3): p.212-215.doi: 10.1097/dad.0000000000000972 . | Open in Read by QxMD
  18. Guarneri C, Bevelacqua V, Polimeni G. Embolia cutis medicamentosa (Nicolau syndrome). QJM. 2011; 105 (11): p.1127-1128.doi: 10.1093/qjmed/hcr194 . | Open in Read by QxMD
  19. Wilbrand J-F, Wilbrand M, Schaaf H, Howaldt H-P, Malik C-Y, Streckbein P. Embolia Cutis Medicamentosa (Nicolau Syndrome) after Endodontic Treatment: A Case Report. J Endod. 2011; 37 (6): p.875-877.doi: 10.1016/j.joen.2011.01.004 . | Open in Read by QxMD
  20. Bolognia J, Jorizzo J, Schaffer J. Dermatology: 2-Volume Set. Elsevier ; 2012
  21. Barbieri JS, Rodriguez O, Rosenbach M, Margolis D. Incidence and Prevalence of Granuloma Annulare in the United States. JAMA dermatology. 2021; 157 (7): p.824-830.doi: 10.1001/jamadermatol.2021.1847 . | Open in Read by QxMD
  22. Cyr PR. Diagnosis and management of granuloma annulare. Am Fam Physician. 2006; 74 (10): p.1729-34.
  23. Wang J, Khachemoune A. Granuloma Annulare: A Focused Review of Therapeutic Options. Am J Clin Dermatol. 2017; 19 (3): p.333-344.doi: 10.1007/s40257-017-0334-5 . | Open in Read by QxMD
  24. Tong LX, Penn L, Meehan SA, Kim RH. Necrobiosis lipoidica.. Dermatol Online J. 2018; 24 (12).
  25. Aróstegui Aguilar J, Diago A, Carrillo Gijón R, et al. Granulomas in Dermatopathology: Principal Diagnoses - Part 1. Actas Dermo-Sifiliográficas (English Edition). 2021; 112 (8): p.682-704.doi: 10.1016/j.adengl.2021.07.011 . | Open in Read by QxMD
  26. Young A, Koduri G. Extra-articular manifestations and complications of rheumatoid arthritis. Best Pract Res Clin Rheumatol. 2007; 21 (5): p.907-927.doi: 10.1016/j.berh.2007.05.007 . | Open in Read by QxMD
  27. Hubail A, Belkharoeva R, Tepluk N, Belerosova T. Lupus pernio (Besnier-Tenneson syndrome): A rare form of sarcoidosis. Dermatology Reports. 2018; 10 (2).doi: 10.4081/dr.2018.7696 . | Open in Read by QxMD
  28. Terziroli Beretta-Piccoli B, Mainetti C, Peeters MA, Laffitte E. Cutaneous Granulomatosis: a Comprehensive Review. Clin Rev Allergy Immunol. 2018; 54 (1): p.131-146.doi: 10.1007/s12016-017-8666-8 . | Open in Read by QxMD
  29. Molina-Ruiz AM, Requena L. Foreign Body Granulomas. Dermatol Clin. 2015; 33 (3): p.497-523.doi: 10.1016/j.det.2015.03.014 . | Open in Read by QxMD
  30. Sajjan V, Swamy M, Lunge S, Pandit A. Livedo reticularis: A review of the literature. Indian Dermatology Online Journal. 2015; 6 (5): p.315-321.doi: 10.4103/2229-5178.164493 . | Open in Read by QxMD
  31. Xeroderma pigmentosum. . Accessed: December 17, 2020.
  32. Lucero R, Horowitz D. Xeroderma Pigmentosum. StatPearls. 2020.
  33. Black JO. Xeroderma Pigmentosum. Head and Neck Pathology. 2016; 10 (2): p.139-144.doi: 10.1007/s12105-016-0707-8 . | Open in Read by QxMD
  34. Gruber R, Sugarman JL, Crumrine D, et al. Sebaceous gland, hair shaft, and epidermal barrier abnormalities in keratosis pilaris with and without filaggrin deficiency.. Am J Pathol. 2015; 185 (4): p.1012-21.doi: 10.1016/j.ajpath.2014.12.012 . | Open in Read by QxMD
  35. Poskitt L, Wilkinson JD. Natural history of keratosis pilaris.. Br J Dermatol. 1994; 130 (6): p.711-3.doi: 10.1111/j.1365-2133.1994.tb03406.x . | Open in Read by QxMD
  36. Jackson JB, Touma SC, Norton AB. Keratosis pilaris in pregnancy: an unrecognized dematosis of pregnancy?. W V Med J. ; 100 (1): p.26-8.
  37. Angiosarcoma - National Cancer Institute. Updated: February 27, 2019. Accessed: April 6, 2020.
  38. Gaballah AH, Jensen CT, Palmquist S, et al. Angiosarcoma: clinical and imaging features from head to toe. Br J Radiol. 2017; 90 (1075): p.20170039.doi: 10.1259/bjr.20170039 . | Open in Read by QxMD
  39. Tambe SA, Nayak CS. Metastatic Angiosarcoma of Lower Extremity.. Indian dermatology online journal. ; 9 (3): p.177-181.doi: 10.4103/idoj.IDOJ_92_17 . | Open in Read by QxMD
  40. Doolittle J, Walker P, Mills T, Thurston J. Hyperhidrosis: an update on prevalence and severity in the United States. Arch Dermatol Res. 2016; 308 (10): p.743-749.doi: 10.1007/s00403-016-1697-9 . | Open in Read by QxMD
  41. Kettelhut EA, Traylor J, Roach JP. Erythema Ab Igne. StatPearls. 2020.

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