Post-scabietic nodules: Mimicker of infantile indeterminate cell histiocytosis and potential diagnostic pitfall

Area of Science:

• Dermatology
• Histopathology
• Pediatrics

Background:

• Indeterminate cell histiocytosis (ICH) is an exceptionally rare disorder with unknown etiology.
• Patients typically exhibit dermal nodules composed of indeterminate cells, resembling Langerhans cells but lacking Birbeck granules.
• The clinical presentation of ICH is variable, with outcomes ranging from spontaneous resolution to aggressive disease progression.

Observation:

• Rare instances of ICH-like reactions have been documented following scabies infestations and arthropod bites (ticks, mosquitos).
• This report details a successfully treated case of indeterminate cell-rich post-scabetic nodules in an 8-month-old boy.
• The lesions mimicked ICH but were associated with a prior scabies infestation.

Findings:

• Histopathological examination revealed nodules rich in indeterminate cells.
• The patient, an otherwise healthy infant, showed a positive response to treatment.
• Literature review identified similar ICH-mimicking lesions in the context of scabies.

Implications:

• Accurate interpretation of ICH-mimicking lesions requires careful consideration of the clinical context, particularly in cases of scabies.
• Distinguishing these indolent lesions from true ICH is crucial to avoid unnecessary patient anxiety and overly aggressive treatment strategies.
• This case underscores the importance of a comprehensive diagnostic approach in pediatric dermatology.