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.