Localized episcleral ALK-positive histiocytosis: a novel adult presentation confirmed by ALK gene rearrangement.
Latha K Abraham, Mobin Paul, Marian Pauly et al.
✦ AI-curated · Sources linked
Case in brief
A 36-year-old woman presented with an episcleral nodule that resembled nodular scleritis. An excisional biopsy revealed foamy histiocytes and Touton-type giant cells, with strong ALK1 expression and confirmed ALK gene rearrangement. Although a suspicious inguinal node was found, it was reactive. After excision, local recurrence occurred, and treatment with alectinib led to symptomatic improvement.
What made this case unusual
This case is notable for being the first documented instance of isolated episcleral ALK-positive histiocytosis in an adult, expanding the known anatomical spectrum of this condition.
Diagnostic / clinical pearl
Clinicians should consider ALK-positive histiocytosis in cases of atypical histiocytic infiltrates, particularly when presenting as ocular lesions.
Why it matters
Routine ALK1 screening in atypical histiocytic infiltrates can facilitate accurate diagnosis and enable access to targeted therapies, improving patient outcomes.