Racemose cysticercosis presenting as cystic neck swelling.

Cysticercosis is a parasitic infection caused by the larvae of the tapeworm Taenia solium which occurs in neural and extraneural forms. Latter commonly involves subcutaneous tissue, skeletal muscles, and eyes. Head and neck sites commonly involved are buccal mucosa, tongue, and lips. It presents as single or multiple submucosal/cutaneous firm nodules. We report a case of cysticercosis of the supraclavicular region of the neck where it presented as a large soft cystic swelling. The diagnosis was made by sonography and confirmed by gross and microscopic examination to be racemose cysticercosis. This is a very rare cause of a neck swelling not reported previously in the literature.

INTRODUCTION

Human cysticercosis is a parasitic infection caused by encysted larvae of Taenia solium with humans as dead-end hosts. Cysticercus cellulosae and Cysticercus racemose are the two larval forms of T. solium in tissues. Infection can be caused by either of the two forms or sometimes with both.

It is one of the most common parasitic diseases worldwide and endemic in developing countries like India.[1] It occurs in neural and extraneural forms. Extraneural forms commonly involve eyes, skeletal muscles, and subcutaneous tissue, where it presents as single or multiple submucosal/cutaneous firm nodules measuring 1-1.5 cm in size. Head and neck sites most commonly involved are buccal mucosa, tongue, and lips.[2] In neck, there are reports of presentation as swelling in the submandibular region and in posterior triangle of neck.[34] In all the previous reports, the presentation was a firm nodular or rubbery swelling, not more than 2 cm in size. We report a case of racemose cysticercosis presenting as a large cystic mass in the supraclavicular region of the neck extending behind the clavicle which is probably the first such presentation in the literature and very rare in extracranial sites.

CASE REPORT

A 60-year-old tribal female patient presented with a 3 month history of right supraclavicular neck swelling. She denied any history of trauma, pain, fever, or constitutional symptoms. She belonged to lower socio-economic stratum and consumed mixed diet. There was no history of consuming pork.

Examination revealed a soft swelling in the right supraclavicular region of approximately 6 cm×7 cm in size, mobile and non-tender. There were no other palpable swellings in any other part of the body. Rest of the ear, nose, throat (ENT) examination was normal. Initially, it appeared to be a lipoma. Ultrasonography (USG) of neck revealed an ill-defined cystic mass of approximately 11×5 cm in the right supraclavicular region with internal septations and small cysts in it which was not markedly differentiable from underlying muscle and connective tissue [Figures 1 and 2]. FNAC revealed non-specific inflammation. Blood investigations showed eosinophilia with a raised absolute eosinophil count of 1152/cu3 and differential leukocyte count (DLC) with eosinophils of 35%. Other investigations were normal. Stool examination showed no ova or cysts.

Figure 1

USG showing cystic mass with internal septations and small cysts in it. No scolex is seen

Figure 2

USG showing cystic mass with internal septations and small cysts in it. No scolex is seen

The patient was taken for an excisional biopsy. The operative findings revealed an approximately 10 cm, cystic mass, adherent to underlying musculature deeply seated in the supraclavicular region which extended behind the clavicle but without any intrathoracic or intraspinal extension [Figure 3]. Grossly, the cystic mass was multiloculated and filled with clear, straw-coloured fluid. The wall of the sac was thick and contained numerous fluid-filled transparent yellow coloured vesicles within it, the largest of which measured nearly 2 cm. It was not possible to remove the entire sac as it extended deep behind the clavicle. So a part of the sac and its contents including the cysts were sent for histopathology. Microscopic examination showed complex branching of the bladder wall displaying a tegumental layer, subtegumental nuclei, and loose connective tissue. Suckers and hooklets were not seen (H and E ×100) [Figure 4]. Based on the above findings of gross and microscopic examination, a diagnosis of racemose cysticercosis was made. The patient was put on albendazole 400 mg for 7 days. The swelling disappeared completely.

Figure 3

Post- operative photograph showing the incision site which marks the site for supraclavicular neck swelling (pre-op. photo not available)

Figure 4

Microscopic examination (H and E ×100) showing complex branching of the bladder wall and the absence of scolex

DISCUSSION

The racemose cysticercus is the term often used for the aberrant cysticercus of T. solium. The racemose form is a non-viable degenerated cyst and is characterized by the absence of scolices and rostellar hooks.[5] It assumes this form apparently due to the influence of the surrounding tissues such as base of the human brain. It may be a form of sterile coenurosis. The presence of degenerated scolices in some specimen favors T. solium as the etiological agent.[6]

This infection is mainly described in cases of neurocysticercosis where it presents mainly in basal subarachnoid cisterns and intraventricular leading to obstructive hydrocephalus. Only rarely has this entity been described in extra-cranial forms. Our literature search yielded only four cases of extracranial form of racemose cysticercosis reported till date. A case of racemose form has been reported presenting as a subcutaneous cyst in the interscapular region in which the infection was thought to have resulted from direct inoculation into the wound.[7] In our case, no such history was there. A case has been reported as early as 1895 by Firket at the heart wall.[8] The third report was of anterior abdominal wall swelling, in which the scolex body was relatively well preserved, and the probable theory of transformation into racemose form was genetic rather than degeneration of the scolex.[8] One more extracranial presentation was in the thyroid with both cellulosae and racemose forms in the same patient.[9]

Ultrasonography can be used as an initial investigation for diagnosing cysticercosis. On high resolution, C. cellulosae appears as an elliptical or round, well-defined, cystic lesion with an eccentric hyperechoic area within it.[10] This hyperechoic area is the scolex. In our case, the absence of scolex and multiloculated appearance with large size was not going in favour of C. cellulosae and favored the racemose form.

Gross examination and microscopy form the definitive diagnosis of cysticercosis. Racemose cysticercosis is characterized by larger size (4-12 cm) in contrast to C. cellulosae, where the maximum size is 1.5-2 cm, multiloculation with large translucent vesicles, with big tails and a variable appearance resembling ‘bunches of grapes’.[6] On gross examination, our case appeared to be racemose cysticercosis.

The racemose form of cysticercosis is characterized by an intense proliferation of the bladder wall after the degeneration of the scolex. Hence, microscopy of the racemose form in contrast to C. cellulosae, shows multiple convolutions of the tegument, absence of scolex and the proliferating zones which are two to three times thicker than the remaining parts of the bladder. Subtegumental and parenchymal layers are also thicker. Due to the absence of scolex, they are known as sterile.[5]

Other differential diagnosis includes cestode larval cysts of Taenia multiceps (coenurosis), which contain numerous scolices whereas those of Echinococcus granulosus (hydatid cysts) are considerably larger with internal daughter cysts and have a characteristic laminated wall. Human coenurosis represents an infection by the metacestode larval stage (coenurus) of any one of four species of dog tapeworms: T. multiceps, Taenia serialis, Taenia brauni, and Taenia glomerata.