Discussion
Splenic tumors are relatively rare. In fact, Bostick WL encountered 10 cases among 80,527 people (2). There are various histological types, including benign primary tumors, such as lymphangioma, hamartoma, and hemangioma; malignant primary tumors, such as malignant lymphoma and angioblastoma; and metastatic tumors (3-5). The most common type of primary benign splenic tumor is hemangioma, almost all of which occur as solitary lesions (6). However, there have been a few reports about cases involving multiple splenic tumors (7) (8). On the other hand, malignant primary splenic tumors, such as angioblastoma, are very rare. However, their prognosis is quite poor (6). The clinical presentation of splenic tumors is highly variable (9); therefore, we must learn how to differentiate among them. Although Heller suggested a diagnostic and follow-up strategy for splenic tumors, which is currently used worldwide (1), challenging cases are sometimes encountered.
We experienced two cases of splenic hemangioma with different clinical presentations and imaging findings.
In case 1, we suspected angiosarcoma because of the following findings: 1. The tumors enlarged. 2. The tumors were heterogeneous and poorly demarcated. (10) Although we initially considered hemangioma, large splenic tumors sometimes mimic angioblastoma (11). In cases of splenic angiosarcoma, surgery is the only curative treatment, and hence, the chance to resect such tumors must not be missed. This was the reason why we performed splenectomy. It might have been better to have conducted a magnetic resonance imaging (MRI) scan. S.Y. Choi reported that contrast-enhanced dynamic and diffusion-weighted MRI are useful for distinguishing between benign and malignant splenic tumors (12).
In case 2, we suspected a metastatic tumor derived from adenocarcinoma of the ascending colon because of both the patient’s medical history and the rapid enlargement of the tumor. Solitary splenic metastases are rare, but they can occur in some cases (13). It may have been better to perform a biopsy of the tumor. Although in Japan splenic biopsies are hardly performed due to fears of causing intraabdominal bleeding or tumor dissemination, they are reported to be a safe and effective way of distinguishing among splenic tumors (14) (15) (16) (17) (18). Heller recommended that biopsies should be performed as a second diagnostic step for splenic tumors that are suspected of malignancy (1). On the other hand, Cho reported a case in which severe complications occurred after a biopsy of a splenic tumor (19). All things considered, biopsying splenic tumors is quite effective; however, with recognition of the potential complications, clinicians should take sufficient precautions such as antibiotic therapy, and preparation for an urgent surgery (splenectomy in some cases).
Laparoscopic splenectomy for hemangioma was first performed by Hodge in 1895 (8). Due to a fear of bleeding, the hand-assisted method is usually selected in the cases involving giant splenomegaly. For splenic tumors, laparoscopic splenectomy is superior to classical open surgery because the laparoscope makes it possible to see the whole abdomen from various angles. This was particularly useful in our case 2, as we initially suspected that the tumor was a metastatic lesion, and hence, it was important to rule out other types of metastases, such as dissemination.
In summary, there are a wide variety of splenic tumors. The Heller’s diagnostic pathway (Fig. 1) is helpful as a diagnostic tool in them (1). For further evaluation, contrast-enhanced MRI and tumor biopsies should be considered. Also, patients should be informed that even benign tumors (which mainly measure >1 cm) can rupture (20) and cause acute abdomen. In cases of splenomegaly, laparoscopic resection with/without the hand-assisted method should be considered.