[Anatomoclinical and immunohistochemical study of 8 cases of dermatomyofibroma]. / Étude anatomoclinique et immunohistochimique de 8 cas de dermatomyofibromes.

INTRODUCTION: Dermatomyofibroma (DMF) is a rare, benign tumour that is little-known among clinicians. However, it has typical clinical, histological and immunohistochemical features that distinguish it from other fibrous tumours. METHOD: We report herein on the clinical, histological and immunohistochemical aspects of eight cases of DMF identified between 2008 and 2019 at the dermatopathology laboratory of Strasbourg. RESULTS: Five men and three women of average age at diagnosis of 21 years and 9 months (range: 9 to 54 years) were included. Lesions ranged in size from 1 to 11cm. Most cases involved the upper body (6 cases), with one case on the abdomen and one on the side. The lesions presented as a solitary asymptomatic red or reddish brown nodule or plaque that gradually developed. The plaques were hard and caused functional discomfort on movement of the neck. Well-circumscribed spindle cell proliferation was noted in the reticular dermis parallel to the epidermis, without mitotic figures or cytological atypia. The subcutis was infiltrated in 5 cases. Expression of calponin was positive in all cases but one, while that of caldesmon, PS100 and desmin was negative. Expression of smooth muscle actin was positive in 2 cases, and both cases were also positive for stromylesin-3. CD34 was positive in 2 cases. DISCUSSION: DMF is an extensive tumour capable of attaining large diameters and must be completely excised. The main differential diagnoses of DMF are dermatofibrosarcoma protuberans, dermatofibroma, fibrous hamartoma, myofibromatosis and cheloid. It can be identified based on various factors, whether clinical (young age, extensive lesion), histological (horizontal proliferation in the reticular dermis) or immunohistochemical (positive expression of calponin).

[Acute localized exanthematous pustulosis following heparin calcium injections]. / Pustulose exanthématique aiguë localisée après injections d'héparine calcique.

BACKGROUND: Acute localized exanthematous pustulosis (ALEP) is a rare variant of acute generalized exanthematous pustulosis and is also defined by diagnostic criteria established by the EuroSCAR study group. Some twenty cases of ALEP have been described in the literature. PATIENTS AND METHODS: A 61-year-old woman suddenly developed erythematous and edematous lesions after subcutaneous heparin calcium injections in the thighs, with bullous detachment at the center of the lesions and multiple vesicles and non-follicular pustules on the edges. These lesions were centered around the injection points. There were no other skin lesions and no lesions on the oral mucosa, and the patient was apyrexial. The skin biopsy revealed an intracorneal pustule with spongiosis, as well as a prominent infiltrate of lymphocytes, neutrophils and eosinophils in the dermis, with no necrotic keratinocytes. We confirmed a definite diagnosis of ALEP, with a score of 10/12 according to the EuroSCAR criteria. A favorable outcome was quickly obtained after discontinuation of heparin injections, with only post-inflammatory pigmented macules. DISCUSSION: This case shows that heparin calcium can lead to ALEP, thus contraindicating further administration of this substance. Other causative factors consist chiefly of systemic antibiotics, spider bites and exposure to certain plants. This case is remarkable in terms of the limitation of lesions to heparin calcium injection sites.