It is a brief story, but let’s be honest – one of a kind. A man had a tapeworm. The tapeworm was ill. The illness was malignant tumour. The patient died with metastasis in lungs, liver, adrenal glands and lymph nodes. Now you see why such a prestigious magazine as New England Journal of Medicine published such a ordinary (at the first sight) case report study.
Taeniasis isn’t something extraordinary. Hymenolepsis nana, the dwarf tapeworm, is the most common human tapeworm. As estimated, up to 75 million people are carriers and the prevalence amongst children is as high as 25% in some areas. Infection is usually asymptomatic. As its name implies, it is a tiny parasite, rarely exceeding 40 mm long and 1 mm wide. Hymenolepsis nana can develop normally within larval fleas and beetles. Direct contaminative infection by eggs is probably the most common route in human cases.
A 41-year-old man in Colombia presented to hospital with various, but non-specific symptoms: fatigue, fever, cough, and weight loss of several months’ duration. He had received a diagnosis of HIV infection in 2006, but he didn’t undergo a therapy. Lab tests showed a dramatic decline in the CD4 cell count, which indicated a serious crisis in his immunity. Numerous Hymenolepsis nana eggs and Blastocystis hominis cysts were found in stool sample. The CT examination result was crucial: it showed multiple lumps in lungs (dimensions up to 4,5 cm) and similar transformations in liver and adrenal glands. Cervical, abdominal and thoracic lymph nodes were enlarged. The conclusions were obvious. Malignant neoplasm – it’s not necessary to have a proper medical knowledge or insight to make such a diagnosis. For further examinations (needed to fit the right therapy) the doctors cut out one of the cervical lymph nodes and took samples from the pulmonary lumps. Well, this is where it gets a little wild, my dear.
Samples from lymph-node and lung biopsies revealed monomorphic, undifferentiated cells. The proliferative cells had overt features of a malignant process, but their small size suggested a nonhuman origin.
That’s the point. Available staining methods normally used for tumour diagnosis turned out to be completely rubbish. The examinations spanned longer, the patient’s condition was getting worse, the lymph nodes were growing (5-cm cervical lymph nodes are a sort of big thing, don’t you agree?). Not knowing what is the problem, the doctors limited treatment to antiparasitic and antiviral therapy, which wasn’t sufficient. The ultimate test results were available 72 hours before the patient’s death – it turned out that the strangely -looking infiltration genetically suit tissues of the unwanted “visitors” of the patient, but with some variations caused by mutations. The doctors had to state the diagnosis out of the common run. The patient was attached and killed by the neoplasm, which derived from the organism living in his tissues–a tapeworm. Proliferation in the immunosuppressed host may have allowed somatic mutations to accumulate in the Hymenolepsis nana stem-cell population, ultimately leading to malignant transformation.
We all know that tumours may be related with multiple infectious factors (including worms), we know that there are some rare types of infectious neoplasms (but found only on non – human species). We know (don’t feel unread if you hear about it for the first time 😉) that invertebrates also can have malignancies and in some rare cases they can mutually infect themselves. In humans, spreading tumorigenesis is extremely rare – through transplantations or through placenta during labour. It seems that we have found another twist – few and far between we deal with such surprises.
- Malignant Transformation of Hymenolepis nana in a Human Host. A Muehlenbachs, J Bhatnagar, CA Agudelo, A Hidron, ML Eberhard, BA Mathison, MA Frace, A Ito, MG Metcalfe, DC Rollin, GS Visvesvara, CD Pham, TL Jones, PW Greer, A Vélez Hoyos, PD Olson, LR Diazgranados, SR Zaki; New England Journal of Medicine 2015;373:1845-1852
- Lethal invasive cestodiasis in immunosuppressed patients. PD Olson, K Yoder, LF Fajardo L-G, AM Marty, S van de Pas, Claudia Olivier, DA Relman; Journal of Infectious Disease 2003;187(12):1962-6
- Radiographic and Pathological Features of Malignant Hymenolepsis nana.
- Scolex of the dwarf tapewormhttp://www.cdc.gov/dpdx/hymenolepiasis/gallery.html#hnanaadults
- H. nana egg in stool sample; Oregon State Public Health Laboratory http://www.cdc.gov/dpdx/hymenolepiasis/gallery.html#hnanaeggsPVA