A 91-year-old man was referred to our hospital with a subcutaneous nodule on the right elbow that had gradually enlarged, with linear wound bleeding. He was being treated with oral aspirin for arrhythmia. After 4 weeks, the mass was still bleeding and had enlarged to 44 x 66 mm in size (Fig. 1a). Enhanced computed tomography (CT) showed a well-demarcated mass with poor contrast on the right elbow (Fig. 1b). Laboratory tests revealed a hemoglobin level of 5.6 g/dL and a platelet count of 11.7x104 /µl. Since the mass had enlarged rapidly and was bleeding, we suspected a malignant tumor and performed an excisional biopsy (Fig. 1c). A histopathological examination revealed a clot that occupied the majority of the mass, abundant fibrous vascular hyperplasia (Fig. 1d, e), cholesterin clefts (Fig. 1f, g), inflammatory granulation tissue composed of lymphocytes and histiocytes (Fig. 1f, h), and hemosiderin deposition (Fig. 1f, i). No malignant cells were observed in any samples. Four weeks later, skin grafting was performed, and no local recurrence has been identified for the two years since the procedure.
CEH was first described by Friedlander et al. in 1968, and parameters defining the disease were established by Reid et al.1 in 1980. CEH chronically and gradually swells over a period of one month to several years and can occur not only in the soft tissue of the skin but also in the thoracic or abdominal cavity2. A recent review by Negoro et al. suggested that the male–female ratio is 3.8:1, and the age of onset is 7–87 years. In 39% of cases, there was a time lag of more than one year between symptom awareness and consultation3. Although the pathogenesis of CEH remains unclear, several hypotheses have been proposed. One is that chronic inflammation caused by accumulated blood and debris promotes angiogenesis, leading to re-accumulation of blood. Further, CEH has been reported to originate from osmotic gradient changes due to the disintegration of hematoma components4. A histopathological feature of CEH has been reported to be a three-layered capsule5. The outer layer has thick fibrous tissue containing hemosiderin deposits and macrophages, the middle layer has loose connective tissue, and the inner layer has granular tissue containing red blood cells and fibrin-like material. The histology of the present case showed no typical three-layered capsule structure. The formation of hemosiderin deposits and cholesterol clefts suggested that several weeks had passed since the hematoma formed. In addition, inflammatory granulation tissue at the bottom of the hematoma means that the tumor may have been partially encapsulated. Moreover, the lesion was located in a joint, and the rapid growth of the tumor implies that the encapsulated hematoma may have ruptured.
Several imaging methods assist doctors in diagnosing CEH, with the main purpose being to distinguish them from malignant tumors. Typically, CT scans of CEH lesions show a cystic mass with a well-defined border and internal heterogeneity, sometimes with calcification inside the mass. Contrast-enhanced CT scans show a faint contrast-enhanced capsule and the leakage of contrast medium into the mass, reflecting a leakage of blood6. In magnetic resonance imaging (MRI) of CEH, a “mosaic sign” consisting of multiple internal signal intensities associated with hemolytic products in T2-weighted images has been described7. Also, a mixture of hypointense and hyperintense areas on T1- and T2-weighted images has been reported8. The heterogeneous signal pattern of CEH corresponds to the collection of fresh and altered blood throughout the lesion. Positron emission tomography (PET)-CT is a powerful tool for differentiating malignant tumors from other tumors; however, FDG uptake has been observed not only in malignant tumors, but also in inflammatory tissues. Reportedly, CEH lesions could show SUVmax 3–5 accumulation in the capsule9; thus, the results of PET-CT may not be definitive.
To find the characteristics of cutaneous CEH, we reviewed the English literatures describing such cases. A search of the PubMed website (https://pubmed.ncbi.nlm.nih.gov/) found 72 cases of CEH in extra-cutaneous lesions: 52 in the thorax, 15 in the abdominal cavity, and 5 in other locations (Table 1). 51 cases of cutaneous and intramuscular CEH were also identified. Among the 51 case, anemia was observed in 3 cases, was not observed in 3 cases, and was not clearly described in 45 cases. 7 cases involved anticoagulant administration, 26 did not, and 18 had no clear description of any such administration. A history of trauma or surgery was noted in 33 cases, 11 cases had no history of trauma or surgery, and in 9 cases, no information was provided (Table 2). Cases with extra-cutaneous CEH have been reported to be associated with anemia and thrombocytopenia. A review of CEH cases including those with extra-cutaneous lesions revealed that 5.2% had been administered anticoagulants10. From our review, the presence of trauma or a history of surgery may be a diagnostic clue, but it is unclear whether anemia or anticoagulation may also be diagnostic clues.
Table 1
The locations of CEH cases reported in PubMed
Location | Cases |
Cutaneous/intramuscular | 51 |
Thoracic | 52 |
Intraperitoneal | 15 |
Other | 5 |
Table 2
Information on cutaneous/intramuscular CEH
Anemia |
Yes | 3 |
No | 3 |
Not described | 45 |
Anticoagulant/antiplatelet |
Yes | 7 |
No | 26 |
Undescribed | 18 |
History of trauma/surgery |
Yes | 33 |
No | 9 |
Not described | 9 |