Trichodysplasia spinulosa is a rare folliculocentric polyomavirus infection observed in the setting of immunosuppression. We report a 7-year-old boy with pre-B-cell lymphoblastic leukemia who presented with folliculocentric spiny papules on the face. Histologic evaluation revealed hypertrophic bulbs, an expanded inner root sheath, and numerous brightly eosinophilic trichohyalin granules. We present this case to raise awareness of this rare but recognizable entity and to highlight the availability of appropriate diagnostic and therapeutic modalities.

Hereditary progressive mucinous histiocytosis is a rare, benign, skin-limited form of non-Langerhans cell histiocytosis. We report on a 5-year-old boy who presented in infancy with self-resolving dermal nodules but later developed persistent and progressive erythematous papules on the face and scalp. Histologic evaluation revealed dermal aggregates of S-100/CD1a-negative histiocytes with abundant mucin. We present this case to highlight the evolution of the lesional morphology in infancy and early childhood and to stress the importance of histology in confirming this rare disorder.