Pityriasis lichenoides chronicahttps://en.wikipedia.org/wiki/Pityriasis_lichenoides_chronica
Pityriasis lichenoides chronica is an uncommon, idiopathic, acquired dermatosis, characterized by the groups of erythematous, scaly papules that may persist for months. A biopsy is required for diagnosis.

Diagnosis and Treatment
Blood tests to rule out syphilis
Biopsy to rule out cutaneous lymphoma

      References Pityriasis lichenoides chronica - Case reports 15748578
      A 19-year-old woman came in with a five-year history of small, spotty rashes and raised, yellowish to skin-colored bumps with a ring of fine scales on her torso and arms and legs. Guttate pityriasis lichenoides chronica is an uncommon presentation of this T-cell-mediated disease.