CPC13 Cutaneous crystal storing histiocytosis

Abstract A 43-year-old woman presented with a 3-year history of gradually enlarging lesion on the right upper chest. Her comorbidities included ankylosing spondylitis and recurrent anterior uveitis, she was taking no regular medications. She had systemic symptoms. initially seen by breast team, who organized an ultrasound that showed chronic inflammation, biopsy granulomatous inflammatory tissue. Topical treatment fucidin unsuccessful, referred to dermatology. On examination, 3.5 × 4 cm pink subcutaneous nodule There lymphadenopathy or organomegaly. Investigations revealed low IgA (0.71 g L−1), raised IgM (4.30 L−1) mild thrombocytopenia (141 109 cells L−1). Full blood count; urea electrolytes; liver function tests; IgG; lactate dehydrogenase; thyroid stimulating hormone; serum angiotensin-converting enzyme; autoimmune serology, including antinuclear antigen; Borrelia serology; tuberculosis QuantiFERON; ferritin; erythrocyte sedimentation rate; protein electrophoresis urine Bence Jones were normal negative. Chest X-ray computed tomography thorax, abdomen pelvis did not reveal any evidence underlying malignancy. Repeat skin superficial deep dermal histiocytic infiltrate. At high power, numerous needle-like eosinophilic crystals within histiocytes. periadnexal perifollicular infiltrate lymphocytes plasma cells. Light chain staining lambda light restricted positive IgG The features crystal-storing histiocytosis. Cutaneous histiocytosis is rare condition, only six reported cases. pathophysiology involves accumulation crystalline material cytoplasm It strongly associated haematological malignancy, multiple myeloma, lymphoplasmacytic lymphoma monoclonal gammopathy undetermined significance (Li JJ, Henderson C. crystal storing histiocytosis: report two J Cutan Pathol 2015; 42:136–43). In our case, bone marrow performed given lack symptoms, significant paraprotein imaging. patient currently being managed topical clobetasol propionate 0.05% ointment under annual haematology surveillance immunoglobulins.