Unexplained subcutaneous swelling: Keep echinococcosis in mind! Report of two primary extrahepatic subcutaneous echinococcosis cases and literature review

Abstract

Alveolar and cystic echinococcoses (AE and CE) are parasitic zoonoses, mainly affecting the liver. Primary extrahepatic localizations remain rare and are difficult to diagnose. We report two cases of primary subcutaneous echinococcosis and the largest literature review on the subject. The first case is an alveolar echinococcosis located in the forehead region and the second a cystic echinococcosis in the abdominal wall. To our knowledge, a primary AE location in the face has never been described before. Pre-surgical diagnosis was not made in these two cases. However, it is essential to apply specific measures, depending on the type of echinococcosis (AE or CE), to prevent parasitic dissemination and recurrence. In view of the cases presented here, prolonged albendazole can be a second-line alternative to a surgical strategy. Echinococcosis should be kept in mind for differential diagnosis of soft tissue lesions in any part of the body.

Fig 1. (A-H). Case 1: primary subcutaneous facial alveolar echinococcosis.

(A) Left frontal swelling at diagnosis. (B) Marked regression of the lesion after 6 months of albendazole therapy. (C-D) FDG-PET scan sagittal images before the initiation of albendazole (C) and after 6 months (D), with a significant decrease of the peri-metabolic activity (yellow circles). (E-F). Histopathology of the frontal lesion. (E). Echinococcus (E) multilocularis microcyst (*) delineated by the laminated layer (1), surrounded by an intense granulomatous reaction (2) and the invaded striated muscle (3). Hematoxylin-eosin stain, X10. (F). A typical aspect of E. multilocularis lesion with a microcyst delineated by the laminated layer revealed by the periodic acid-Schiff (black arrow) and surrounded by an intense granulomatous reaction composed of macrophages with epithelioid arrangement (*) and a dense lymphocytic infiltrate (**), X20. (G-H). Thoracic imagings of the alveolar echinococcosis (AE) pulmonary location. (G) Axial CT scan image revealing a mass in the lower lobe of the left lung (white arrow). Transparietal puncture revealed another localization of AE. (H) FDG-PET scan axial image showing the hypermetabolism of this lung lesion (white arrow). E. multilocularis PCR was positive for both skin and lung lesions.

Fig 2. (A-E). Case 2: primary subcutaneous cystic echinococcosis located in the left subcostal area.

The sub-cutaneous swelling had been present for several months and had recently grown and become painful. (A) Thoraco-abdomino-pelvic CT scan, which was the only imaging exam performed prior to surgery: oblique sagittal image showing a subcutaneous heterogeneous, poly-lobulated tissular lesion (yellow circle) with central hypodense portions of rounded morphology and some parietal macrocalcifications. Possible infiltration of the intraperitoneal fat in contact with the thoracoabdominal diaphragm muscle which was suspected of being invaded in its ventral portion. Following this CT scan, the diagnosis of sarcoma was considered, leading to surgical intervention. The intraoperative findings indicated that it was a cystic echinococcosis lesion (B-C) Histopathology of the sub-costal mass. (B) Hematoxylin-eosin stain of the tissue lining the cavity showing an intense granulomatous reaction (black arrows), X9.1. E.granulosus PCR was positive while E.multilocularis PCR was negative. The perilesional inflammatory reaction could be explained by a probable cystic fissuration leading to the patient’s recent symptomatology. (C) Hematoxylin-eosin stain showing acellular elements corresponding to the laminated layer of parasitic cyst, X0.4. (D-E) CT scan evolution after sub-total cystectomy followed by albendazole therapy. (D) Axial image showing the lesion before surgery (white arrow). (E) Axial image of the lesion 3 years later, the patient was still being treated with albendazole. Marked regression and increased calcifications of the cystic echinococcosis lesion (white arrow).

Fig 3. Description of the selection process for articles included in the review in accordance with the PRISMA method.

PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses.