Treatment of progressive nodular histiocytosis: a case report

Progressive nodular histiocytosis (PNH) is an extremely rare type of non-Langerhans cell histiocytosis, characterized by the emergence of hundreds small to large cutaneous papulonodules without spontaneous remission. It can be life-threatening if pharyngeal and laryngeal mucosa were involved, just as we reported in this case. Disfigurement and disabling are common, whereas current treatment options are of limited efficacy. At present, about 20 reported cases can be found through a PubMed search, fewer with treatment options. In this article, we report a unique case of a patient diagnosed with PNH, in whom regorafenib had a remarkably curative effect.

We present the case of a 21-year-old man who developed lesions on his face, trunk, limbs, and exceptionally in the pharyngeal and laryngeal mucosa. Immunohistochemistry showed diffuse CD68 positivity and scattered S-100 positivity, while CD1α, smooth muscle actin (SMA) and B-Raf proto-oncogene, serine/threonine kinase (BRAF) were negative. Histopathological and biochemical examinations confirmed the diagnosis of PNH. The patient underwent facial lesion resections; however, the lesions recurred rapidly within 1 month. In December 2019, treatment with a small multi-kinase inhibitor, regorafenib (120 mg daily for 3 weeks on, and 1 week off), was initiated, and the patient's progress was monitored. After 10 days of administration, the patient's facial lesions began to gradually alleviate, and after 1 month, the lesions in the trunk, limb, and especially the face continued to subside even further. In 2021, the regorafenib dose was subsequently adjusted to 40 mg daily, with intermittent administration. No abnormalities were observed in the routine blood tests, liver, and kidney function results during the follow-ups to date. Presently, the patient's overall condition is good, the lesions are gradually improving, and the patient has returned to normal life and work.

This clinical report supports the future exploration of regorafenib treatment in patients with PNH.