2006 Volume 97 Issue 6 Pages 804-808
A 32-year-old male consulted a hospital with a complaint of left scrotal swelling. Serum hCGβand LDH levels were elevated and computed tomography demonstrated a suspicious small lymphadenopathy in the paraaortic region. Left inguinal orchiectomy was performed. Histological examination demonstrated seminoma. We diagnosed the disease as clinical stage 2A and the patient received 2 courses of chemotherapy with cisplatin, etoposide and bleomycin. After this therapy, the small lymphadenopathy in the paraaortic region did not decrease in size. We considered this lesion a vessel or connective tissue.
Although he achieved clinical complete remission and serum LDH level was normalized, the serum hCGβ level remained low level positive. Urinary hCGβ level after chemotherapy was below the threshold of detectability. We measured the serum from this patient as well as control sera by twoand four-fold dilution with a diluent comprised of mouse serum as a heterophilic antibody-blocking agent. The serum hCGβ level of this patient was obviously decreased; in contrast, control sera were decreased in parallel. The serum hCGβ level of this patient remained low level positive without recurrence for 8 months after chemotherapy. These results strongly suggested that low level of positivity for serum hCGβ in this case was a false positive finding. We consider the measurement of urinary hCGβ and dilution measurement using a heterophilic antibody-blocking agent to be useful methods of distinguishing false positive findings for serum hCGβ.
