B114: Painful cutaneous nodules in chronic neutrophilic leukaemia, JULY 2022.
"Chronic neutrophilic leukaemia (CNL) is a very rare, often clinically aggressive myeloid malignancy with few effective treatment options. Neutrophilic dermatosis of the dorsal hands (NDDH) is an uncommon, localized variant of SWEET SYNDROME (SS), first described in 1995."
"We present the first case, to our knowledge, of NDDH in a case of CNL highlighting the challenge of histopathological differential diagnosis of leukaemia cutis (LC)."
NDDH (a localized variant of Sweet's syndrome) or LC?
NDDH.
- Abrupt onset.
- Good response to steroids.
- "dense dermal infiltrate of mature neutrophils with associated dermal oedema and sometimes prominent leucocytoclasis in the absence of bona fide vasculitis" (white blood cells called neutrophils in the skin and fluid in the dermal skin layer. Swelling of the small blood vessels (vasculitis), but not a primary or true vasculitis which includes the immune system attacking the blood vessels. Vasculitis in SS/NDDH caused by neutrophils releasing noxious substances and severe inflammation).
- SS/NDDH with histiocytoid features. Skin biopsy shows immature cells not mature neutrophils that can be mistaken for histiocytes; immune cells that destroy foreign substances and help fight infection. Sometimes, real or authentic histiocytes are present.
LC.
- Gradual onset.
- Worsens as leukaemia progresses.
- Requires systemic chemotherapy.
- "neutrophils in CNL are immature, on occasions manifesting in atypia, often arranged in a perivascular location with no significant dermal oedema " (immature neutrophils, occasionally, manifesting as abnormally structured cells centred around small blood vessels with no fluid in the dermal skin layer).
- "Immunophenotypic and molecular studies can also establish the presence of blasts in the skin" (blast cells are stem cells that become immature cells).
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NB: Not all NDDH patients have or will develop cancer.