Chondroid metaplasia of peritoneum in absence of prior surgery - A rare presentation with a short review of literature

The presence of chondroid metaplasia in the peritoneum is rare. All cases reported, except one, had a history of prior abdominal surgery.[1,2,3,4,5] We report the second case of chondroid metaplasia of the peritoneum in a patient with no history of prior surgery. A 35-year-old primigravida underwent LSCS for non-progression of labor. At surgery, an irregular white nodule was incidentally found in the omentum and was excised. Grossly, an omental mass was received measuring 4 cm × 3.5 cm × 2 cm composed of fat along with a shell-shaped glistening white nodule measuring 2.5 cm × 2 cm × 2 cm [Figure 1a]. On cut-section, it was translucent and gritty to cut [Figure 1b]. On microscopy, multiple nodules of mature hyaline cartilage undergoing calcification and endochondral ossification were seen surrounded by fibro-fatty tissue and covered by benign mesothelial cells [Figure 1c, d, e]. There was no evidence of inflammation, atypia, or mitosis. A diagnosis of chondroid metaplasia was made based on the histopathological findings.

Figure 1.

a) shell-shaped irregular white peritoneal chondroid nodule surrounded by omental fat; b) cut-section shows smooth, glistening, translucent appearance; c) multiple nodules of mature hyaline cartilage; d) hyaline cartilage (*) surrounded by adipose tissue and mesothelial cells (arrow and inset); e) nodules of hyaline cartilage undergoing calcification and endochondral ossification

Chondroid metaplasia of the peritoneum is described as the presence of nodules of mature cartilage without atypia and in the absence of malignant mesothelial neoplasm, metastatic adenocarcinoma, or fetal implantation.[4]

Eight cases of chondroid metaplasia of the peritoneum have been reported [Table 1]. Five out of eight cases had prior abdominal surgery. In two cases, history was not available. Seven out of eight cases have been reported in females. Only one case has been reported in a male and it was not associated with prior surgery. These cases presented as single or multiple nodules with the involvement of the peritoneum at different sites. All cases were incidental findings on surgery with size ranging from 2 mm to 2 cm in diameter. Grossly, all cases presented as glistening white nodules composed of lobules of mature hyaline cartilage lined by the mesothelium and some showing foci of calcification or ossification.[2,3]

Table 1.

Review of cases of chondroid metaplasia of the peritoneum reported in English literature

Author and year	Sex age	Prior surgery	Number	Size	Location
Roth et al.[1] 1966	F/32	History NA	Single	NA	Serosa over uterine fundus
Fadare et al.[2] 2002	F/53	Culdotomy	Multiple	2 to 7 mm	Mesentery of bowel
Fadare et al.[2] 2002	F/77	TAH with BSO	Single	2 cm	Mesentery of ileum
Houng et al.[3] 2010	F/40	Salpingectomy	Single	16 × 12 × 9 mm	Serosa over uterine fundus
Franceschi et al.[4] 2018	F/74	Hysterectomy	Single	2 × 1.5 × 1 cm	Recto vaginal area
Franceschi et al.[4] 2018	F/40	History NA	Multiple	0.2 to 2 cm	Recto uterine pouch
Nwanze et al.[5] 2018	M/72	No prior surgery	Single	2 mm	Peritoneum at porta hepatis
Present case	F/35	No prior surgery	Single	2 cm	Omentum

NA=not available, TAH = total abdominal hysterectomy, BSO = bilateral salpingo-oophorectomy

The pathogenesis of chondroid metaplasia is uncertain and several theories have been proposed. It may be due to the metaplasia of pluripotent sub-mesenchymal cells in response to injury.[2] This was supported by the fact that most cases of chondroid metaplasia have prior history of surgery. Moreover, cases of osseous, squamous, and Mullerian metaplasia of peritoneum have been reported, which indicated that mesothelial cells have the potential to differentiate into heterologous elements, further giving credence to this hypothesis.[3] Franceschi et al.[4] performed the DNA analysis of two cases of chondroid metaplasia and compared them with that of normal peritoneal tissue and tissue extracted from ovarian teratoma. Both cases and normal tissue showed heterozygosity at each informative microsatellite focus, whereas ovarian teratoma was homozygous at many polymorphic microsatellite loci. These results indicate that peritoneal chondroid nodules arise from pluripotent mesodermal stem cells. On genotypic analysis, the cartilaginous tissue had the same allele as normal tissue and no paternal material was detected, ruling out organized products of conception as the cause of chondroid metaplasia. Hence, the theory of whether chondroid metaplasia represented a mature teratomatous proliferation of fetal rests from conception products seems unlikely. Houang et al.[3] suggested that nodules of chondroid metaplasia could represent chondroma arising from the sub-mesothelial mesenchymal tissue. In the present case, with the absence of prior surgery, this possibility cannot be ruled out.

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