Nodular histiocytic/mesothelial hyperplasia as consequence of chronic mesothelium irritation by sub-phrenic abscess.

摘要

Nodular histiocytic/mesothelial hyperplasia (NHMH) is a benign localized alteration, firstuddescribed in 1975 by Rosai in the hernia sac [1]. Few pulmonary cases have been reported in literatureud[2–6]. Sometimes it has been reported in the pericardium [7,8] or presenting as an inguinaludmass [9]. The ‘mesothelial/monocytic incidental cardiac excrescence’, first described by Weinot et al.udin 1994 [10] is now considered a similar lesion to NHMH [11].udIt consists of a reactive proliferation of histiocytes and mesothelium secondary to chronic irritationudand it has been observed in pleura-damaging processes, such as pneumothorax [5], or as consequenceudof cardiac catheterization, inflammation, mechanical or tumor stimulation [11].udThe rarity of NHMH and the moderate cytological atypia often present, make this lesion difficultudto diagnose. It can be easily confused with primary mesothelial lesions and neoplasms suchudas adenocarcinomas, granulosa cell tumors or Langerhans’ histiocytosis.udWe report a case of pleural NHMH in a patient with a subphrenic abscess, in which no pulmonaryudpathogenic noxa was evident. We hypothesize a transdiaphragmatic chronic irritation as audpathogenetic mechanism underlying NHMH.