Background: Cutaneous Rosai - Dorfman disease (CRDD) is extremely rare variant of idiopathic histiocytic proliferative disorder, which may manifest as a non-specific macules, papules, plaques or nodules ranging in size and colour from yellow - red to red -brown.
Case presentation: A 52-year-old female presented with three gradually enlarging, reddish - brown nodules on the right upper extremity lasting six months. The patients denied fever, weight loss, malaise. Clinical examination and imaging tests showed no sign of lymphadenopathy. A biopsy specimen of a nodule showed a dense dermal polymorphic infiltrate with numerous histiocytes exhibiting emperipolesis phenomenon. Immunohistochemical staining of the histiocytes showed S-100 protein (+), CD68(+), but CD1a (-). Aforementioned findings were consistent with CRDD characteristics. Additionally, a routine serological screening and confirmatory serological tests for syphilis were positive. Syphilis of unknown duration was diagnosed. The IgG antibodies titre against Chlamydia trachomatis was elevated. An isolated sensory impairment over the right trigeminal nerve was found on neurological consultation. Comprehensive gynaecological assessment was carried out because of patient's complaints of bleeding after sexual intercourse and led to diagnosis of cervical cancer. The initial therapy with methotrexate was discontinued after three months due to neutropenia. Further therapy with dapson was ineffective, therefore complete surgical excision was recommended.
Conclusions: CRDD is a rare, benign condition especially difficult to diagnose due to lack of general symptoms and lymphadenopathy. Histopathologic examination with immunohistochemical staining, exhibiting characteristic and reproducible findings play a key role in establishing an accurate diagnosis. In the presented case activated histiocytes demonstrated in a lesional skin might be a response to immune dysregulation related to chronic, untreated sexually transmitted infections and cancer.
Keywords: Rosai-Dorfman disease; emperipolesis; histiocytosis; syphilis.