Case Report: A 69-year-old woman with dermatopathic lymphadenopathy and hypercalcemia after COVID-19 infection

Patient concerns: A 69-year-old female presented with hypercalcemia, recurrent fever, and lymphadenectasis following COVID-19 infection. Positron emission tomography/computed tomography (PET-CT) revealed no suspicious malignancy. Lymph node biopsy from bilateral inguinal areas suggested Langerhans cell histiocytosis, supporting a possible diagnosis of dermatopathic lymphadenitis or rare Langerhans cell histiocytosis. The immunohistology staining showed that the proliferated Langerhans cells in lymph nodes expressed CD68, CD1a, and S100, further supporting the diagnosis of dermatopathic lymphadenitis. Diagnosis and intervention: The patient was diagnosed with dermatopathic lymphadenopathy. The patient underwent a therapy of prednisone acetate at 30 mg per day. Then, glucocorticoid was gradually decreased by 2.5 mg per 2 weeks, until it reached 7.5 mg per day. Salmon calcitonin was subcutaneously injected to decrease the calcium level and relieve pain during hospitalization. Outcomes: During the 3 months of treatment, the systemic symptoms were significantly alleviated. The lymph nodes of the right inguinal area and the serum calcium level decreased to normal. She remained in remission for an additional 4 years. Lessons: Coexistence of the two unrelated diseases, dermatopathic lymphadenopathy and hypercalcemia, was rare. Immune dysregulation and persistent inflammatory responses post-COVID-19 infection may be the potential mechanism for hypercalcemia.