Differential Diagnosis for Generalised Whitish Rash on Body Except on Scalp

• Single most likely diagnosis
  • Pityriasis versicolor: This condition is characterized by a skin infection caused by a yeast-like fungus, leading to patches of discoloration on the skin, typically excluding the scalp. It's a common condition, especially in young adults, and matches the description provided.
• Other Likely diagnoses
  • Vitiligo: An autoimmune condition that causes the loss of pigment-producing cells (melanocytes), leading to white patches on the skin. It can occur anywhere on the body and might spare the scalp, although it often affects the face and hands.
  • Pityriasis alba: A mild, chronic skin condition characterized by small, round, faint patches of hypopigmentation, often seen in children and young adults. It typically affects the face but can appear on other parts of the body, potentially sparing the scalp.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sarcoidosis: A condition where inflammatory cells form lumps known as granulomas in various parts of the body, including the skin. Skin manifestations can include hypopigmented patches, although this is less common. Sarcoidosis can affect multiple organs and has significant implications if not diagnosed and treated.
  • Leprosy (Hansen's disease): A chronic bacterial infection that primarily affects the skin, nerves, and mucous membranes. It can cause light-colored patches on the skin, among other symptoms. Early diagnosis and treatment are crucial to prevent long-term complications.
• Rare diagnoses
  • Idiopathic guttate hypomelanosis: A condition characterized by small, discrete, hypopigmented spots, typically on the arms and legs. It's more common in older adults and those with a history of significant sun exposure.
  • Progressive macular hypomelanosis: A rare condition presenting with large, confluent areas of hypopigmentation, primarily on the trunk. It's often accompanied by a fine scale and can be confused with other conditions like pityriasis versicolor.