The Sampson theory (retrograde menstruation) does not fully explain endometriosis pathogenesis. The 'stem cell' theory proposes bone marrow-derived stem cells contribute. Which histological/immunohistochemical finding in ectopic endometrial lesions best supports a metaplastic or stem cell origin rather than simply transplanted endometrial cells?
- A Presence of CD10-positive stromal cells identical to eutopic endometrial stroma
- B Expression of Hoxa10 and Hoxa11 transcription factors in endometriotic foci
- C Lesions in sites where retrograde menstruation cannot deposit tissue (e.g., pleural cavity, umbilicus, nasal mucosa) ✓
- D Estrogen receptor and progesterone receptor positivity in ectopic glands
Correct answer: C. Lesions in sites where retrograde menstruation cannot deposit tissue (e.g., pleural cavity, umbilicus, nasal mucosa)
Explanation
The occurrence of endometriosis in anatomical locations unreachable by retrograde menstruation — such as the pleural cavity (catamenial pneumothorax), nasal mucosa, umbilicus in males, and perineal scars — cannot be explained by the Sampson transplantation theory and strongly supports alternative mechanisms: coelomic metaplasia (Meyer theory) or haematogenous/lymphatic spread of stem cells/progenitor cells. CD10 positivity, hormone receptor expression, and HOXA gene expression are characteristic of endometriosis but do not distinguish its origin mechanism.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.