[Cytopenia under topical imiquimod in two patients treated with oral hydroxyurea]

BACKGROUND

Aldara^® is a topical immunomodulatory treatment. The risks of systemic passage are minimal. There have been rare reports of systemic adverse effects.

PATIENTS AND METHODS

Case 1. Five sachets weekly of imiquimod were prescribed for Bowen's disease on the forearm in a patient known to have essential thrombocytosis under Hydrea^®. His CBC was normal (6000 leukocytes/mm³, 2200 PMN/mm, 230,000 platelets/mm³). Imiquimod was given in 15 sachets weekly. Fifteen day later, the patient presented bicytopenia (3000 leukocytes/mm³, 1400 PMN/mm³, 119,000 platelets/mm³). Hydroxyurea and imiquimod were suspended until normalization of CBC. Hydroxyurea was resumed without recurrence of the bicytopenia. The patient's history included an identical episode following application of imiquimod. Case 2. Five sachets weekly of imiquimod were prescribed for actinic keratosis on the scalp in a patient known to have primary polycythemia under hydroxyurea. Her CBC was normal except for anemia (Hb 11.5g/L, 160,000 platelets/mm³, 1100 lymphocytes/mm³). Imiquimod was given in 12 sachets weekly. Ten days later, anemia increased (Hb 10g/dL) with lymphopenia (800/mm³) and thrombocytopenia (115,000/mm³). Suspension of imiquimod resulted in normalization of the previous CBC values.

DISCUSSION

. The literature review identified reports of dose-dependent lymphopenia under oral imiquimod but not under Aldara^®. The National Pharmacovigilance Database listed 10 cases of hematological disorders most likely caused by Aldara^®. Hydroxyurea may induce cytopenia, and while it was not considered the sole causative agent in this case, it is likely to have had a triggering role in these patients with blood dyscrasias. Our findings show that misuse of imiquimod carries a potential risk of hematologic abnormality in patients receiving concomitant hydroxyurea, a commonly combined drug.

Severe cutaneous adverse reactions due to inappropriate medication use

BACKGROUND

The proportion of severe cutaneous adverse reactions (SCARs) that could be avoided if medication use was consistent with good medical practice is unknown.

OBJECTIVES

To estimate the proportion of SCARs related to inappropriate medication use.

METHODS

We carried out a retrospective study of all validated SCARs collected in a French registry between 2003 and 2016. For each case, all plausible drugs suspected of inducing SCARs (i.e. not just the drug regarded as 'the most probable') were considered with regard to (i) prescription for an inappropriate indication, (ii) unintentional rechallenge despite a previous allergy to the drug or (iii) self-medication with prescription medicines.

RESULTS

In total, 602 cases were included in the analyses. Antibiotics, anticonvulsants and allopurinol were the drugs most frequently involved, accounting for more than 50% of all cases. All suspected medications were considered to have been appropriately used for 417 of the 602 individuals included in the study population [69·3%, 95% confidence interval (CI) 65·6-73·0] and inappropriately used for 144 individuals (23·9%, 95% CI 20·5-27·3). These inappropriate uses were due mainly to prescriptions for an inappropriate indication (65·8%, 95% CI 58·4-73·2) or unintentional rechallenge (20·9%, 95% CI 14·6-27·2). Allopurinol and co-trimoxazole were the drugs most frequently involved in inappropriate indications. Antibiotics were the largest group involved in unintentional rechallenge. Nonsteroidal anti-inflammatory drugs, available on prescription, were most frequently involved in inappropriate self-medication.

CONCLUSIONS

Our results underline the need for respecting the appropriate indication for drugs in order to reduce the incidence of SCARs. Reducing unintentional rechallenge also seems to be a necessary preventive measure.

[Misdiagnosis of hidradenitis suppurativa continues to be a major issue. The R-ENS Verneuil study]

OBJECTIVE

To provide physicians with an understanding of the factors behind significant delays in the diagnosis of hidradenitis suppurativa (HS) in France.

PATIENTS AND METHODS

This prospective multicentre national study conducted from October 2015 to March 2016 included all patients consulting for HS. Patient data were collected by means of a standardized questionnaire. Univariate and multivariate analyses were conducted to collect factors associated with a significant time to diagnosis of at least 5.5years, defined as the period between the onset of initial clinical signs and the time of formal diagnosis.

RESULTS

The 16 participating centres enrolled 312 patients (62% women), of average age 35years. The average age at onset of HS was 22years. Before formal diagnosis by a dermatologist (64% of cases), 170 (54%), 114 (37%) and 45 (15%) patients had previously consulted at least 3, 5 and 10 general physicians, respectively. The average time between the initial clinical signs of HS, the first dermatology visit and the definitive diagnosis was 6.2 and 8.4 years, respectively. Active smoking (OR adjusted 1.85; P=0.027) and disease onset at a younger age (adjusted OR 0.92; P<0.001) were both associated with significant delays in diagnosis.

CONCLUSION

These results emphasized misdiagnosis among HS patients but did not evidence any association between either sociodemographic or economic characteristics and the existence of significant times to diagnosis.

Trimethoprim-sulfamethoxazole-induced linear IgA bullous disease presenting as toxic epidermal necrolysis

BACKGROUND

Linear IgA bullous dermatosis (LABD) is an autoimmune blistering skin disorder characterized by linear IgA deposits along the dermoepidermal junction. Usually idiopathic, LABD can be drug-induced.

OBJECTIVE

To report the atypical characteristics of a case of trimethoprim-sulfamethoxazole-induced LABD presenting as toxic epidermal necrolysis (TEN).

METHODS

A 63-year-old woman treated with trimethoprim-sulfamethoxazole for Pneumocystis jirovecii infection developed a generalized maculopapular rash with herpetiform lesions, rosette-like lesions, and tense bullae with Nikolsky sign.

RESULTS

Anti-basement membrane zone antibodies were negative, but immunoblot revealed a 160 kDa band corresponding to subepidermal class IgA desmoglein 1. Skin biopsy specimens revealed a subepidermal bulla and direct immunofluorescence showed linear IgA deposition along the basement membrane zone. A diagnosis of toxic epidermal necrolysis was excluded and replaced by trimethoprim-sulfamethoxazole-induced LABD.

CONCLUSION

We report a case of trimethoprim-sulfamethoxazole-induced LABD with a 160 kDa IgA desmoglein 1 found by immunoblotting analysis, probably by epitope spreading.