Lymphomatoid papulosis (LyP) is a rare skin disorder. The overall prevalence rate of lymphomatoid papulosis is estimated at 1.2 to 1.9 cases per 1,000,000 population. [This is a widespread misinterpretation of a 1992 study saying "the period prevalence rate of lymphomatoid papulosis was estimated to be 1.9 per 1,000,000 population for Massachusetts and 1.2 per 1,000,000 population for Pennsylvania". The authors of that study said clearly "Our estimate of 1.2-1.9 cases per 1,000,000 population should be considered a minimum estimate of the prevalence rate". That estimate was based on the 78 patients involved in the study, not the LvP population. The study recruited 11 patients from Massachusetts and 15 from Pennsylvania ]. This rare condition has only been studied in depth since 1968. Presentation
It can appear very similar to anaplastic large cell lymphoma. Type "A" is CD30 positive, while type "B" is CD30 negative.It has been described as "clinically benign but histologically malignant." Treatment
It may respond to methotrexate or PUVA. Prognosis
It can evolve into lymphoma. See also
Cutaneous T-cell lymphoma
Parapsoriasis
Secondary cutaneous CD30+ large cell lymphoma
List of cutaneous conditions

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Detection of a cystic malformation may prompt further investigation, such as amniocentesis, to evaluate for genetic abnormalities in the fetus. Lymphatic malformations may be discovered postnatally or in older children/adults, and most commonly present as a mass or as an incidental finding during medical imaging. Verification of the diagnosis may require more testing, as multiple cystic masses can arise in children. Imaging, such as ultrasound or MRI, may provide more information as to the size and extent of the lesion. Treatment
A baby with a prenatally diagnosed cystic hygroma should be delivered in a major medical center equipped to deal with neonatal complications, such as a neonatal intensive care unit. An obstetrician usually decides the method of delivery. If the cystic hygroma is large, a cesarean section may be performed. After birth, infants with a persistent cystic hygroma must be monitored for airway obstruction. A thin needle may be used to reduce the volume of the cystic hygroma to prevent facial deformities and airway obstruction. Close observation of the baby by a neonatologist after birth is recommended. If resolution of the cystic hygroma does not occur before birth, a pediatric surgeon should be consulted.Cystic hygromas that develop in the third trimester, after 30 weeks gestation, or in the postnatal period are usually not associated with chromosome abnormalities. A chance exists of recurrence after surgical removal of the cystic hygroma.