Pseudomalignancies in Children: Histological Clues, and Pitfalls to Be Avoided

Abstract

The term “pseudomalignancy” covers a large, heterogenous group of diseases characterized by a benign cellular proliferation, hyperplasia, or infiltrate that resembles a true malignancy clinically or histologically. Here, we (i) provide a non-exhaustive review of several inflammatory skin diseases and benign skin proliferations that can mimic a malignant neoplasm in children, (ii) give pathologists some helpful clues to guide their diagnosis, and (iii) highlight pitfalls to be avoided. The observation of clinical–pathological correlations is often important in this situation and can sometimes be the only means (along with careful monitoring of the disease’s clinical course) of reaching a firm diagnosis.

Skin Biopsy in Pediatric Oncology/Hematopoietic Stem Cell Transplantation Patients

“…While a high index of suspicion for Langerhans cell histiocytosis is critical in the appropriate circumstances, it is important to be aware that florid non-neoplastic Langerhans cell infiltrates are a recognized mimic of Langerhans cell histiocytosis and can be seen in a range of common inflammatory processes, including in association with scabies infection, other arthropod assault reactions, and allergic contact dermatitis among others. 6 In addition to clinical and histological features to suggest a trigger for hyperplasia, the use of immunohistochemical staining for cyclin D1 and identification of underlying MAPK activating mutations, which can be found in most cases, can be important in confirming the diagnosis of Langerhans cell histiocytosis. 7,8 After review, 42 cases were considered to show features consistent with graft-versus-host disease.…”