Angiolymphoid hyperplasia with eosinophilia differs from cutaneous CAD because it lacks contracted lymphoid follicles with onion-like mantle zones and perivascular hyalinization, while the infiltrate usually contains large numbers of eosinophils. Cutaneous sinus histiocytosis with massive lymphadenopathy (SHML) demonstrates a more prominent proliferation of epithelioid histiocytes (S-100+, CDla—), some of which have abundant granular, eosinophilic cytoplasm. Hyalinized vessels and abundant plasma cells may be seen in SHML but onion-like structures are lacking. Another clue to SHML is emperipolesis of histiocytes. Study of TCR rearrangements is helpful in distinguishing CAD from skin involvement by angioimmunoblastic T-cell lymphoma. The neoplastic follicles in cutaneous follicular center cell lymphoma and marginal zone lymphoma are usually larger than those seen in CAD, with an expanded irregular meshwork of follicular dendritic cells. Collagen and vascular hyalinization is absent. Light-chain restriction and clonal IgH rearrangements are found in many instances, facilitating the differential diagnosis.
Cutaneous Castleman disease
Clinical features Elderly people Multiple or solitary nodules Histological features
Onion-like follicles with reduced mantle zone and gerninal centers depleted of follicular dendritic cells Hyalinized collagen and vessels Plasma cells Immunophenotype
Follicles: CD21+, CD35+, KiM4p+, KiM4+, KiFDClp+, R4/23+ Mantle zone: polyclonal B cells Molecular biology
No TCR or IgH rearrangements Laboratory evaluation
Relevant only in POEMS syndrome Treatment
Excision, radiation and/or chemotherapy Clinical course Benign
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