Differential Diagnosis for 23y/o Female with Bone Pain and Red, Swollen Rash on Extremities

• Single Most Likely Diagnosis
  • Sarcoidosis: This condition can cause bone pain due to bone involvement and skin manifestations such as erythema nodosum, which presents as red, swollen rash on the extremities. The combination of systemic symptoms like bone pain and specific skin findings makes sarcoidosis a plausible diagnosis.
• Other Likely Diagnoses
  • Lupus: Systemic Lupus Erythematosus (SLE) can cause a wide range of symptoms including bone pain (due to arthritis or osteonecrosis) and various skin rashes. The disease's variability and the presence of both bone and skin symptoms make it a consideration.
  • Psoriatic Arthritis: This condition combines the swollen, scaly skin of psoriasis with joint pain and arthritis, which could be perceived as bone pain. The rash associated with psoriasis could fit the description provided.
  • Rheumatoid Arthritis: While primarily known for causing joint pain and swelling, rheumatoid arthritis can also lead to systemic symptoms and, less commonly, skin manifestations that might fit the description.
• Do Not Miss Diagnoses
  • Osteomyelitis: An infection of the bone, osteomyelitis can cause significant bone pain and, if the infection spreads to the skin, could result in red, swollen areas. Missing this diagnosis could lead to severe consequences, including the loss of the limb or sepsis.
  • Cellulitis: A bacterial skin infection, cellulitis can cause redness, swelling, and pain in the affected area. If not treated promptly, it can lead to more serious infections.
  • Meningococcemia: A severe infection caused by Neisseria meningitidis, meningococcemia can present with a rash and, in severe cases, can lead to sepsis and death. The rash can initially appear as small, red, pinpoint spots and can evolve.
• Rare Diagnoses
  • Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues, some types of Ehlers-Danlos syndrome can lead to skin hyperextensibility and joint hypermobility, potentially causing bone pain and unusual skin findings.
  • Sweet Syndrome: Also known as acute febrile neutrophilic dermatosis, Sweet syndrome is characterized by the sudden onset of fever, leukocytosis, and tender, erythematous, well-demarcated papules and plaques. It can be associated with systemic symptoms and could fit the description given, although it is less common.