A 27-year-old secretary had been suffering from recurring plantar petechiae for 8 months. Lesions had been first noticed by her relatives, who referred that the patient presented also irritability, difficulty in concentration, and a marked reduction of her job performance. Although laboratory test and clinical examination results were otherwise normal, she had previously been labelled with diagnoses such as ‘vasculitis’, ‘capillaritis’, ‘vitamin deficiency’ and ‘chronic fatigue syndrome’. The decisive diagnostic clue was provided by rope bondage marks on the wrists and ankles. After the accompanying relative had left, and after an initial opposition, the patient aggressively admitted she used to undergo sadomasochistic practices (pricking and scratching of the soles with small sharp objects) in the setting of a heterosexual love affair started 10 months earlier. The patient, whose family relations were conflicting and uncooperative, alleged she reached great sexual satisfaction through such practices; moreover, she refused any psychiatric referral or drug treatment, and forbade the author to reveal the true nature of her lesions to her relatives. The differential diagnosis of plantar purpuras, the complicated framing of the case in the setting of paraphilias (sadomasochism, partialism) and of sexual addiction, as well as ethical, legal, and deontological implications, are discussed. The entangled familial setting is analyzed as well. Albeit skin lesions related to sadomasochism have been reported in the literature, they are generally severe (anogenital burns) or self-explanatory (revealing bizarre lesions), unlike the case described here.