21^st World Dermatology Congress

Rosai Dorfman Disease (RDD), also known as Sinus Histiocytosis with Massive Lymphadenopathy (SHML) is a rare entity, which presents as painless cervical lymphadenopathy. Rarely does RDD involve the skin only. When it does, the disease is referred to as cutaneous RDD. We present a case of cutaneous RDD, an uncommon disease, which can be difficult to diagnose clinically and histopathologically, and challenging to treat. 

 

A 67-year-old female presented with a 9-month history of asymptomatic reddish brown papules and plaques overlying a movable indurated subcutaneous nodule on the left inner thigh. No lymphadenopathies were present. Review of systems was negative.  Medical history was noncontributory. Wedge biopsy was done.  Histopathology revealed nodular and diffuse dermatitis. Lymphocytes and plasma cells were seen within the cytoplasm of several large histiocytes, consistent with emperipolesis.  Immunohistochemistry was positive for CD68 and S-100, and negative for CD1a. Further evaluation through neck, chest & mediastinum, and whole abdominal CT scans revealed no systemic involvement. A final diagnosis of cutaneous RDD was made. 

 

Although the skin is one of the most common extranodal sites for RDD, cutaneous  RDD without nodal involvement is rare, accounting for about 3% of reported cases.  The lesions are painless, and it is less likely to have systemic involvement and constitutional features compared to nodal RDD. Owing to its favorable outcome and spontaneous resolution, cutaneous RDD should not be confused with other benign or malignant lesions.  Hence, aggressive treatment such as excision should not be presented as first-line of treatment.  In our patient, the lesion has decreased in size to 40% in 2 years with no other associated signs and symptoms.   

 

The importance of thorough diagnosis, circumspect management, and adequate patient education should be emphasized.