In the absence of microorganisms on skin biopsy and low clinical suspicion of infection, vancomycin and meropenem were discontinued on day 35 and empiric treatment with oral prednisone 40 mg daily was initiated on day 38, which resulted in a rapid improvement of the patient’s rash within 24 hours with complete resolution after a 7-day course of prednisone. Notably, the patient manifested concomitant recovery of the ANC. The patient completed his last cycle of consolidation therapy with ATRA and idarubicin without further complications and remains in molecular remission.
Neutrophilic dermatoses (NDs) are a group of disorders characterized by neutrophilic cutaneous infiltration without evidence of infection. These entities include SS, pyoderma gangrenosum, subcorneal pustular dermatosis, erythema elevatum diutinum, and neutrophilic eccrine hidradenitis.2 Neutrophilic dermatoses commonly present with acute onset of skin lesions and fever. Underlying systemic disease such as malignancy, inflammatory disease, autoimmune disease, pregnancy, and medications are known to be associated with ND. Although the rash clinically was reminiscent of SS, the histopathologic features were inconsistent with SS. Sweet syndrome typically presents with extensive monotonous neutrophilic infiltrates in the dermis. In this case, the neutrophilic infiltrates were localized and associated with the hair follicle, in the dermis and subcutis, and were accompanied by a granulomatous inflammation. Neutrophilic eccrine hidradenitis clinically is similar to SS and the distinction usually is made on the basis of histopathologic examination. Lack of the neutrophilic infiltrates within the eccrine secretary coils in our case did not support the diagnosis of neutrophilic eccrine hidradenitis.
Although the histopathologic features of the presented case were inconsistent with a particular subtype of ND, the clinical presentation and response to corticosteroids suggested that this unusual mixed inflammatory skin reaction might share a similar pathophysiologic mechanism.
A review of 20 patients with sterile neutrophilic folliculitis demonstrated an association with systemic diseases including cutaneous T-cell lymphoma, monoclonal gammopathy, Crohn disease, and autoimmune disorders.3 In acute myeloid leukemia, sterile neutrophilic folliculitis may be part of the initial presentation and responds to induction chemotherapy.4 An extensive search of PubMed articles indexed for MEDLINE using the search terms folliculitis, APL, and neutrophilic dermatoses did not reveal any prior reports of isolated neutrophilic folliculitis or mixed granulomatous reaction in patients with APL in molecular remission.
Although rare, cases of ATRA-induced SS have been reported. Some authors believe that SS in APL may represent a partial form of differentiation syndrome.5 Those cases usually occur during first induction. However, a recurrent episode of differentiation syndrome cannot be excluded in this patient.
A cutaneous reaction to chemotherapy with mitoxantrone as a cause also should be considered, given that the rash occurred only during the second cycle of consolidation therapy when mitoxantrone was used. However, this rash is rare in patients receiving mitoxantrone. The late onset of the rash from the time of last mitoxantrone administration argues against this diagnosis.
In summary, we describe an unusual presentation of a sterile mixed inflammatory skin reaction that occurred in a setting of neutrophil recovery following a second cycle of induction chemotherapy with ATRA and mitoxantrone for APL.