Mycoplasma pneumoniae is well known to be a frequent cause of atypical pneumonia worldwide. However, it may also present with a wide variety of clinical features, including cutaneous symptoms, which are not widely recognised. Urticarial vasculitis occurring with M. pneumoniae has been described to occur in only one other case report. This amalgamation of non-specific clinical symptoms and signs can lead to a diagnostic dilemma. We describe a case of M. pneumoniae infection presenting with extrapulmonary manifestations and urticarial vasculitis, which was misdiagnosed as adult-onset Still's disease (AOSD). Had immunosuppressive therapy been commenced for AOSD in the presence of undiagnosed infection, this may have resulted in potentially serious consequences. This case highlights the need to remain vigilant about diagnosing M. pneumoniae as its serological diagnosis may take weeks and it has many extrapulmonary manifestations, which can masquerade as other conditions.

Summary Cutaneous lesions of the legs have been linked to Helicobacter species in a number of patients with X‐linked agammaglobulinaemia (XLA), a primary immunodeficiency. We describe a 26‐year‐old patient with XLA, who was referred with an extensive skin ulcer that enlarged gradually over the course of 7 years. The ulcer resembled pyoderma gangrenosum (PG), and extended from below the knee to the ankle. The man (who has sex with men) was negative for human immunodeficiency virus. Helicobacter cinaedi was identified by 16S ribosomal (r)DNA PCR analysis from a biopsy of the lesion. This fastidious organism has been implicated previously in causing unexplained skin macules in one other patient with XLA. We suggest that early consideration of infection with Helicobacter species in immunocompromised patients who present with unexplained cutaneous lesions is important, as a prolonged antibiotic course can lead to clinical improvement.

Eccrine nevi are rare lesions characterized by a sharply demarcated area of localized hyperhidrosis. We present an 11-year-old girl with an eccrine nevus on her right lower forearm. To the best of our knowledge, this is the first case successfully controlled with topical glycopyrrolate wipes.

Summary Gastrointestinal stromal tumours (GISTs) are mesenchymal tumours arising in the gastrointestinal tract. Early detection, before metastasis occurs, is important as complete surgical excision achieves cure. Approximately 85% of GISTs are associated with mutations in the KIT gene, and although the majority of GISTs are sporadic, familial GISTs have been identified. Several families with multiple GIST tumours have also been described with various cutaneous findings including hyperpigmentation, multiple lentigines, vitiligo and urticaria pigmentosa. We discuss a 6‐year‐old boy who presented with an unusual pattern of hyperpigmentation in association with a family history of GIST. A causative KIT mutation was identified in DNA from the pigmented skin and from the resected GIST, and the patient was referred to the Paediatric Gastroenterology department for GIST screening. The term ‘GIST cutaneous hyperpigmentation disease’ has been suggested previously for the association of familial GIST with cutaneous hyperpigmentation caused by a germline KIT mutation.

We report a unique case of ascending cutaneous lymphangitis in a 72-year-old immunocompromised man from which a newly described Nocardia species was isolated by 16S ribosomal gene sequencing. Treatment with trimethoprim-sulfamethoxazole resulted in successful resolution of symptoms. To the best of our knowledge, this is the first case report of N. veterana implicated in causing ascending cutaneous lymphangitis.