[Congenital cutaneous Langerhans histiocytosis. Apropos of 7 cases]

Seven cases of congenital Langerhans' cell histiocytosis (LH) are reported, with emphasis on clinical and immunohistochemical features. This is a polymorphic disease at birth. In 4/7 cases, the diffuse, generalized rash could be classified as cutaneous Letterer-Siwe disease (LSD); 3/4 remained purely cutaneous and healed in less than 3 months; whereas the fourth-one persisted, pulmonary lesions appeared, and the infant died on his 40th day. In 3/7 cases, the clinical diagnosis at birth was either a Blueberry Muffin Baby (BMB) or Hashimoto-Pritzker type LH (HPLH); the lesions healed rapidly, although one cas was contradictory: typical BMB at birth, histology mimicking a monoblastic cutaneous leukemia, no T.O.R.C.H. syndrome, normal bone marrow, immunophenotyping of LH, auto-involution; 2/3 were MZ twins, both with few lesions. We would like to stress the fact that the clinical spectrum of LH should include BMB, which, however, in most cases must be considered a differential diagnosis. Regarding cutaneous congenital LH, an eponymic classification (LSD, HPLH) is difficult to follow strictly, because overlapping pictures are observed. There is a wide spectrum of cutaneous congenital LH. The main problem at birth is the lack of prognostic criteria. Neither the presence of the rash at birth, nor its type and extension, is necessarily evidence of risk of systemic disease. Cases of HPLH involute, as also do cases of cutaneous LSD, and the "Blueberry Muffin" type of LH; overlapping clinical aspects exist. Histopathological data, electron microscopy or immunohistochemistry, define LH, but they do not enable the outcome to be predicted.(ABSTRACT TRUNCATED AT 250 WORDS)