CPC12 An unusual case of paraneoplastic sarcoid presenting as dactylitis

Abstract A 40-year-old Nepalese man presented with a 2-year history of progressive swelling of his fingers and toes, with associated haemorrhagic destruction of the nail plates. He had a background of diet-controlled diabetes and no regular medications. Examination revealed localized asymptomatic firm swelling in the middle and distal phalanges of both hands, with friable erosive changes on the distal phalanges of the left middle and ring fingers, and associated nail plate destruction. The toes were also affected with nail dystrophy and nodules over the interphalangeal joints. Sensation was intact and peripheral nerves were not palpable. He was systemically well with no fever, weight loss or muscle weakness. Investigations revealed a raised erythrocyte sedimentation rate (14 mm h−1) and serum angiotensin-converting enzyme (71 U L−1). However, soluble interleukin-2 receptor was not raised. Connective tissue screen, protein electrophoresis, and cryoglobulins were negative. Viral and syphilis serology screen and interferon-γ release assay were negative. Skin swabs for bacterial and mycology culture were negative. Tissue bacterial culture, tuberculosis cultures and mycobacteria polymerase chain reaction were negative. X-rays of the hands and feet revealed destructive changes to the distal phalanges of multiple fingers and toes, with lytic lesions of thickened trabeculae forming a honeycomb pattern, surrounded by soft-tissue swelling. Computed tomography of the chest, abdomen and pelvis displayed low-volume lymphadenopathy. Subsequent axillary lymph node biopsy showed granulomatous lymphadenitis. A positron emission tomography–computed tomography scan revealed increased uptake in the right lobe of the thyroid, and a cervical lymph node biopsy revealed metastatic thyroid papillary carcinoma. A skin biopsy showed hyperkeratosis and acanthosis, with the whole depth of the dermis infiltrated by multiple non-necrotizing granulomas. The cutaneous nerves were spared. Special stains were negative, including Wade–Fite, periodic acid–Schiff and acid-fast bacillus stains. A diagnosis of sarcoid dactylitis was made and treatment commenced with a reducing course of prednisolone 40 mg daily, along with hydroxychloroquine 200 mg twice daily. This resulted in rapid resolution of the nodules and haemorrhagic nail involvement within a few weeks. He also underwent a total thyroidectomy and selective neck dissection, followed by radioiodine treatment. This is the first reported case of dactylitis as a manifestation of paraneoplastic sarcoid. Sarcoidosis has been linked to an increased risk of neoplasia, with frequently overlapping presentations. Sarcoid dactylitis is rare, occurring in about 0.2% of cases of sarcoid. It presents with asymmetrical involvement of fingers and toes, causing soft-tissue swelling of the middle and distal phalanges, with bone destruction and cysts in a honeycomb pattern. The radiological findings can therefore aid diagnosis. Our case highlights the rare initial presentation of dactylitis as a manifestation of paraneoplastic sarcoid.