Pityriasis Lichenoides et Varioliformis Acuta and Psoriasis Vulgaris: Mere Coincidence or a Rare Association?

Correspondence To the Editor: A 23‑year‑old otherwise healthy male presented with diffuse, erythematous, nonpruritic papules on the trunk and extremities, which gradually developed over 1 month [Figure 1a and 1b]. The patient was afebrile and had no other systemic symptoms. His personal and family histories were unremarkable. He denied any drug intake or episode of infection before the onset. Head, hands, feet, and mucosa were spared. No lymphadenopathies were detected. Histopathological examination revealed full‑thickness epidermal necrosis, parakeratosis, vacuolization of the basal layer, and superficial perivascular infiltration of lymphocytes and histiocytes in the dermis. Exocytosis was prominent, and intraepidermal red blood cells could be seen [Figure 1c]. A diagnosis of pityriasis lichenoides et varioliformis acuta (PLEVA) was established. He was prescribed with oral prednisolone (30 mg/d) for 2 weeks, and complete remission was obtained. A follow‑up visit at 3 years later showed no evidence of recurrence of PLEVA. Five years after the onset of PLEVA, some new erythematous scaling plaques appeared on his chest with no symptoms. Physical examination revealed multiple symmetrical, varying‑sized, well‑defined erythematous plaques with characteristic silvery‑white scales on the scalp, trunk, axillae, and upper limbs [Figure 1d and 1e]. Auspitz's sign was noted. Nails and joints were spared. Histopathological examination revealed confluent parakeratosis with neutrophil aggregates (Munro microabscess), diminution of the granular cell layer, acanthosis, papillary edema, tortuous and dilated capillaries, and a superficial perivascular chronic inflammatory infiltration, consistent with psoriasis vulgaris [Figure 1f]. He was treated with topical calcipotriol compounds, which resulted in excellent response. Pityriasis lichenoides (PL) is an uncommon group of self‑limited inflammatory dermatitis with clinical manifestations over a continuous spectrum. PLEVA and PL chronica (PLC) are generally considered to be the two ends of this spectral disease. Although PLEVA is considered to be a lymphoproliferative reaction, its etiology remains unknown. It may be an inflammatory response triggered by extrinsic agents, an inflammatory response secondary to T‑cell dyscrasia, or an immune complex‑mediated hypersensitivity. The most widely accepted hypothesis invokes an immunologic response to a variety of antigens, including microbial pathogens, certain drugs, and vaccinations. Psoriasis is a very common immune‑inflammatory dermatosis that can be provoked by environmental triggers. The pathologic process is considered as consequences of immunological dysfunction, which involves an intimate crosstalk between the innate and the adaptive immune systems. Psoriasis can be provoked by nonspecific triggers such as trauma, chemical irritants, and infections. [2] Th1, Th2, Treg, and Th17 cells are important immune …