Histologic criteria for the diagnosis of pityriasis rubra pilaris.

Even though the clinical appearance of pityriasis rubra pilaris is often distinctive enough to allow specific diagnosis of it, criteria for its histologic diagnosis have not yet been well defined. On the basis of a study of 55 cases of pityriasis rubra pilaris, we found the following histologic features helpful for diagnosis throughout most of the course of the disease: alternating orthokeratosis and parakeratosis in both vertical and horizontal directions; focal or confluent hypergranulosis; thick suprapapillary plates; broad rete ridges; narrow dermal papillae; and sparse superficial perivascular infiltration, mostly of lymphocytes. Plugging of follicular infundibula by cornified cells was seen only in biopsy specimens that came from lesions that were clinically indubitably follicular. Psoriasis has many histologic features in common with pityriasis rubra pilaris, but evolving and fully developed lesions of psoriasis have neutrophils in mounds of parakeratosis, thin rete ridges, thin suprapapillary plates, broad dermal papillae, and mixed inflammatory cell infiltrates of variable density.

Eosinophilic pustular folliculitis in patients with acquired immunodeficiency syndrome. Report of three cases.

Eosinophilic pustular folliculitis is a rare disease. Highly unusual is its occurrence in three patients with acquired immunodeficiency syndrome (AIDS), described herein. This association may be the result of immunologic aberrations that are described in AIDS and may represent an abnormal reaction to skin saprophytes and dermatophytes.

Seborrheic-like dermatitis of acquired immunodeficiency syndrome. A clinicopathologic study.

We studied twenty-five skin biopsies from twenty-one patients with acquired immunodeficiency syndrome or its prodrome who presented with the "seborrheic dermatitis" associated with acquired immunodeficiency syndrome and compared them with an equal number of biopsies from patients with seborrheic dermatitis who had neither acquired immunodeficiency syndrome nor its risk factors. We found that although the eruption in acquired immunodeficiency syndrome closely resembles seborrheic dermatitis, histologically it is distinctive because it shows spotty keratinocytic necrosis, leukoexocytosis, and a superficial perivascular infiltrate of plasma cells and, frequently, neutrophils that show occasional leukocytoclasis. In long-standing lesions, hyperkeratosis is often present. None of these histologic features are commonly encountered in seborrheic dermatitis, psoriasis, or other eruptions known to us.

Incidence of metabolic alkalemia in hospitalized patients.

Analysis of 13,430 arterial blood samples demonstrated that metabolic alkalemia was the most common acid-base disturbance encountered in the hospital setting, being present in 51% of patients with abnormal acid-base status. Respiratory alkalemia was encountered in 29%, respiratory acidemia in 27%, and metabolic acidemia in only 12%. Evaluation of those blood gases with metabolic alkalemia, using 95% confidence-limit bands for acid-base disturbances, showed that the metabolic alkalemia was pure in 70% of the cases, mixed with respiratory acidemia in 18%, and combined with respiratory alkalemia in 12%. The adverse effects of alkalemia may be subtle but often significant. Alveolar hypoventilation in response to metabolic alkalemia, without evidence of primary respiratory disease, was more frequent than is generally suspected. This hypoventilation often directly results in hypoxemia, as well as atelectasis with worsened ventilation/perfusion match-up. Alkalemia shifts the oxyhemoglobin dissociation curve to the left, increasing hemoglobin's affinity for oxygen, thus, limiting oxygen release at the tissue level. The presence of metabolic alkalemia makes it more difficult to wean patients from assisted ventilation. A clearer understanding of the frequency and significance of metabolic alkalemia should lead to more appropriate therapy to prevent or correct this acid-base disturbance and should result in a decreased morbidity and mortality in critically ill patients.