Pemetrexed-induced pseudocellulitis is a rare adverse effect associated with an antineoplastic agent, pemetrexed. It presents as painful peripheral oedema and erythema.
Other names for the disorder are pemetrexed-associated pseudocellulitis, chemotherapy-related acute lipodermatosclerosis-like eruption, acute lipodermatosclerosis-like eruption from pemetrexed, and pemetrexed-induced skin sclerosis.
Pemetrexed-induced pseudocellulitis is not due to bacterial infection and does not improve on antibiotics.
Patients can develop pseudocellulitis within two or three days of receiving pemetrexed or up to six to eight months after receiving it.
Pemetrexed is often used to treat:
Risk factors for pemetrexed-induced pseudocellulitis include:
However, not all patients with pemetrexed-induced pseudocellulitis have these risk factors.
The exact pathophysiology of pemetrexed-induced pseudocellulitis is not known. What is known:
Pemetrexed-induced pseudocellulitis presents with the following features:
Less common presentations include:
Erythema is more difficult to observe in skin of colour compared to white skin, which may result in misdiagnosis. Hyperpigmentation is often pronounced.
Complications from pemetrexed-induced pseudocellulitis are due to chronic inflammation resulting in permanent hyperpigmentation and fibrosis.
Misdiagnosis as cellulitis leads to:
Cellulitis is often suspected when there is localised erythema and oedema, most often affecting a lower leg. A form of pseudocellulitis must be considered in the following circumstances:
Pemetrexed-induced pseudocellulitis should be considered in patients with pseudocellulitis who have been treated with pemetrexed.
Histology typically shows panniculitis, oedema, epidermal spongiosis, and infiltration of lymphocytes and eosinophils.
Other investigations may include:
Generally, pemetrexed-induced pseudocellulitis improves within days to a few weeks when treated with steroids. Erythema and oedema resolve but hyperpigmentation and sclerosis may persist for months or longer.
