Pure cutaneous relapsing Langerhans cell histiocytosis in an adult

ARTICLE

The histiocytic syndromes represent a group of rare diseases characterized by the proliferation of mononuclear phagocyte system cells [1]. Migrating from the blood to other compartments these cells form macrophages, Kupffer cells, histiocytes, microgliacytes, osteophages, interdigital cells, and Langerhans cells [2].

The histiocytic syndromes were classified in 1987 [3] by the "Histiocytic Society" into the following classes:

* Class I diseases or Langerhans cell histiocytosis (previously called Histiocytosis X).

* Class II disorders or histiocytosis of mononuclear phagocytes: reticulohistiocytoma, xanthogranuloma, hemophagocytic lymphohistiocytosis, etc.

* Class III diseases or malignant histiocytic disorders: acute monocytic leukemia, malignant histiocytosis, and histiocytic lymphoma.

A class I histiocytosis with pure cutaneous localizations has recently been described [4].

We report a case of relapsing Langherans cell histiocytosis with an exclusively by cutaneous localization in an adult.

Case report

A 50-year-old man had a 3 cm ulcerated, nodular, and asymptomatic lesion located on the right cheek (Fig. 1). The nodule had appeared three months earlier, and a progressive growth was reported by the patient.

Histopathological examination of the lesion disclosed a massive dermal infiltrate with no evident grenz zone (Fig. 2a). The dermal cell population was mainly composed of mono- and multinucleated histiocytes; these showed abundant eosinophylic cytoplasm with sharp outlines and pleomorphic nuclei (Fig. 2b), often with deep folds of the nuclear membranes. Mitotic figures, as well as focal areas of hypodermal infiltration were additional worrisome histological features. A mild inflammatory infiltrate, mainly composed of polymorphonuclear granulocytes and small lymphocytes, was also evident.

Immunohistochemically, the proliferating cells showed positive reactions for S100 protein (Fig. 2c), CD1a, and CD4; the anti-CD3 polyclonal antibody gave negative results.

Electron microscopy revealed large cells with folded nuclei and abundant cytoplasm. Several rod-shaped cytoplasmic structures were detected and their morphology was similar to Birbeck's granules (Fig. 3).

Clinical examination of the patient, including ophthalmological and endocrinological examination, was normal. Total body computed tomography, bone scanning, and abdominal echography showed no significant changes.

After two months, two similar lesions appeared on the left cheek and back. However, spontaneous regression of the lesions occurred after six months. New lesions appeared after two years on the left labial nose furrow and back. Further histopathological, immunohistochemical and ultrastructural examination of the new lesions showed findings similar to those described above. All the lesions had the same evolution, characterized by spontaneous resolution with scarring. After a five year follow-up no new lesions were observed.

The clinical, histopathological, and ultrastructural features of our case suggested the diagnosis of benign, pure cutaneous, relapsing Langerhans cell histiocytosis.

Discussion

Today, the Langerhans cell histiocytoses (LCH) are recognized as a reactive process rather than a true neoplastic disease [5]. This observation, together with the recent reports of self-healing forms, is going to change the prognostic value, as well as the management of this group of diseases.

In addition to the three classic forms of LCH (the so-called histiocytoses X: eosinophilic granuloma and Hand-Shuller-Christian and Letterer-Siwe diseases), since 1973 Hashimoto and Pritzker, and other authors [6-9] have described a self-healing group of LCH with pure cutaneous involvement.

Our case is peculiar because the self-healing, pure cutaneous localization of a LCH was diagnosed in a 50-year-old patient and not in a newborn, as expected from the classic Hashimoto-Pritzker's form [4, 8, 9]. Clearly, the histopathological diagnosis of cutaneous LCH must be followed by a careful search for any systemic localization. Once a diagnosis of pure cutaneous LCH has been established, the occurrence of self-healing forms (with a possible chronic relapsing course) even in adults must be borne in mind. Therefore, long term follow-up is strongly advised before involving patients in aggressive protocols [10-12].

REFERENCES

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