6 September 2006 – Case of the Week #58


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We thank Dr. Ankur Sangoi, Stanford University, Stanford, California (USA) for contributing this case.  We invite you to contribute a Case of the Week by sending an email to NPernick@PathologyOutlines.com with microscopic images (any size, we will shrink if necessary) in JPG or GIF format, a short clinical history, your diagnosis and any other images (gross, immunostains, EM, etc.) that may be helpful or interesting.  We will write the discussion (unless you want to), list you as the contributor, and send you a check for $35 (US) for your time after we send out the case.  Please only send cases with a definitive diagnosis. 


Case of the Week #58


Clinical history


The patient is a term newborn with abnormal fetal ultrasound and MRI, leading to a lobectomy after birth.


Microscopic images: image #1; #2; #3; #4; #5


What is your diagnosis? 


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Congenital cystic adenomatoid malformation, type II




Congenital cystic adenomatoid malformation is a rare hamartomatous disorder, affecting 1 per 25,000 births.  It is characterized by variably sized cysts lined by columnar-type (“adenomatoid”) epithelium.  It may represent a maturation defect, and is associated with neonatal distress, other lung conditions or stillbirth.


The current classification includes 5 types, discussed in more detail in the Lung-non tumor chapter of PathologyOutlines.com.  The present case contains small cysts up to 2 cm.  On high power, these resemble dilated bronchioles lined by ciliated epithelium that are separated by normal alveoli.  This type is associated with other malformations, not present in this case, and a poor prognosis.

These entities appear to be developmental, not neoplastic.  A recent study showed no karyotypic abnormalities and no p53 mutations (Pediatr Dev Pathol 2006;9:190).


Since some of these lesions regress spontaneously, current recommended treatment in asymptomatic infants is close follow up, with elective surgery for persistent lesions within the first year of life (Arch Dis Child Fetal Neonatal Ed 2006;91:F26, Int J Gynaecol Obstet 2005;89:99)


Additional references: Archives 2002;126:934, AJSP 2003;27:1139



Nat Pernick, M.D.
PathologyOutlines.com, LLC
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