Dr Kirana Pailoor, DCP, DNB, Department Of Pathology, Father Muller Medical College, Mangalore-575003, Karnataka, India. Email: firstname.lastname@example.org
A 50-year-old woman, who underwent left mastectomy 2 years ago for infiltrating ductal carcinoma, came for follow up. A routine ultrasound of the abdomen detected a lesion in the spleen, which was suspected to be an abscess/metastasis. There was no apparent involvement of other organs such as liver, bone, lungs etc. The patient underwent splenectomy and recovered without any complications. On histopathological examination, it was diagnosed to be splenic metastasis from breast carcinoma. We present this case because of the rarity of the lesion and also as a reminder to be cognizant of one of the less likely differential diagnosis of an intraparenchymal solid splenic mass.
Splenic tumors are very rare and present a diagnostic dilemma.1–4 The differential diagnosis of splenic tumors includes hemangioma, lymphangioma, hamartoma, hemangiosarcoma, malignant lymphoma and metastatic carcinoma.1,2,5 Several careful autopsy studies have shown that the spleen is involved in metastatic carcinoma in 2.3% to 7.1%1,6 of cases. Splenic metastasis tends to occur late in the course of disease, rarely produces clinical symptoms, and hence is seldom seen by the surgical pathologist or the clinician.1,6,7 Visceral metastasis from breast carcinoma to liver, lungs, bone, kidney etc. are more prevalent but isolated splenic metastasis (absence of metastasis to other organs) is exceedingly rare.
A 50-year-old woman, who was operated for carcinoma of the left breast (tumor, node and metastasis staging: T2 N2 M0) by modified radical mastectomy 2 years ago had come to our hospital for follow up. The histopathological examination of the specimen indicated infiltrating duct carcinoma with two metastatic lymph nodes. Other possible sites of spread revealed no metastasis. There was no family history of breast cancer. The patient received chemotherapy (cyclophosphamide, methotrexate and 5-flourouracil; six cycles) and was on tamoxifen. During the previous 2 years, she did not suffer from any significant illness.
On physical examination, the patient was found to be pale but moderately nourished. Abdominal examination revealed a mass 3 cm below the left coastal margin that moved with respiration, directed towards right iliac fossa (splenomegaly). The liver was not palpable. There was no other palpable mass or ascites. Vaginal and rectal examinations were normal. The mastectomy bed, contralateral breast and both axilla were normal. Hematological analysis showed mild anemia. Biochemical parameters including liver function tests and renal function tests were within normal limits. An ultrasonogram of the abdomen showed splenomegaly with a large cystic lesion in the spleen. Computed tomography of the abdomen and pelvis revealed an enlarged spleen containing a well circumscribed solitary hypodense area measuring 6 × 5 cm.
The other visceral organs were normal. Computed tomography of the chest was normal. Hence radiologically, splenic abscess or metastatic lesion to the spleen were considered. As there were no other lesions, the patient was prepared for laporotomy and splenectomy. Perioperatively, the spleen was enlarged with an irregular surface and adhesions. The liver, bowels and viscera were normal; there was no ascites. Splenectomy was done and the postoperative period was uneventful.
The spleen was 11 × 8 × 4 cm, weighed 500 g with an irregular surface. Cut section showed a fleshy growth with extensive areas of hemorrhage and necrosis, 6 cm in diameter, with a peripheral rim of splenic tissue all around (Fig. 1). Microscopic examination showed sheets, trabeculae, cribriform pattern and nests of tumor cells having eosinophilic cytoplasm with pleomorphic hyperchromatic vesicular nuclei with prominent nucleoli (Fig. 2a–c). Dense areas of hemorrhage and necrosis and a few mitotic figures were noted. Tumor cells were seen involving predominantly white pulp and also some areas of red pulp. These histopathological findings of the splenic tumor were similar to that of the prior features of carcinoma breast. The tumor cells of the primary tumor were arranged in solid sheets, syncytial aggregates, cords and cribriform pattern. They were large pleomorphic with vesicular nuclei and prominent nucleoli (Fig. 2d). The immunohistochemical study of both primary and metastatic tumor was done outside, which were estrogen receptor, progesterone receptor and HER 2-neu negative. Hence the diagnosis was established as splenic metastasis from infiltrating duct carcinoma of the breast, not otherwise specified.
Metastatic lesions of the spleen are very rare. Paget examined 735 breast cancer patients at necropsy, but only 17 (2%) involved splenic metastases. Berge showed the spleen to be involved by metastasis in 7% of all cancer and as the 10th most common organ involved by metastasis.6 The incidence of splenic metastasis by autopsy studies ranges from 2.3% to 7.1%. Small superficial subcapsular foci associated with peritoneal dissemination are observed in ovarian cancer. However metastases from solid tumors to the spleen due to hematogenous dissemination are confined to the splenic parenchyma and should not be confused with peritoneal spread. Most splenic metastases are a part of multivisceral metastatic disease.1,8 Studies (mainly necropsies) reveal that the most important primary sites, for metastasis to spleen, are skin melanoma (34%), breast carcinoma (12%), ovary (12%), lung (9%), and colon and rectum (10%).1,2,5,8–10
The incidence appears to be the same in both the sexes, but it is more frequently found in the elderly.2 Two cases of breast carcinoma diffusely metastasing to the spleen, presenting with idiopathic thrombocytopenic purpura have been reported.6 Published cases of isolated splenic metastasis worldwide is less than 25.7 Only one case of isolated splenic metastasis from carcinoma of the breast has been reported.8
Splenic metastases can present as three main macroscopic patterns such as macronodular, micronodular and diffuse.1 Our case presented as a macronodular type with macroscopically discernible solitary large mass surrounded by a peripheral rim of splenic tissue. Autopsy studies conducted by several authors have concluded that the metastatic disease involving spleen may not be identified easily. Lam and Tang,3 in their 25-year clinicopathologic study have proposed several explanations for relative paucity of splenic metastasis (i) the sharp angle made by the splenic artery, which makes it difficult for tumor emboli to enter the spleen; (ii) the rhythmic contractile nature of the spleen, which squeezes out the tumor emboli and prevents its lodging in the spleen; (iii) the absence of afferent lymphatics to bring metastatic tumor to the spleen; and (iv) antitumor activity due to a high concentration of lymphoid tissue in the spleen and the production of antiangiogenesis factor-angiostatin. Several other studies also have supported the above reasons.1,6,8,10
The differential diagnosis of splenic mass includes splenic tumors such as malignant lymphoma, vascular tumors, inflammatory pseudotumor, metastatic carcinoma and non-neoplastic lesions such as abscess and fungal infections. Though, a few of the lesions such as hamartoma, inflammatory pseudotumor or an abscess can radiologically mimic a metastatic tumor, there is generally no confusion on histologic grounds.
In the case of isolated metastasis to spleen, splenectomy is justifiable, since it has a low complication rate and potential long term survival is higher.1,8 It is difficult to predict the clinical behavior of a solitary metastasis to the spleen accurately, because of the rarity of this lesion.1
In conclusion, isolated splenic metastasis is an exceedingly rare event. Due to the recent advances in the knowledge of the metastatic process, it seems likely that late occurrence of solitary splenic metastasis might develop from early blood–borne micrometastasis within the spleen, after a period of clinical latency.1,2 This case is a reminder to be cognizant of one of the less likely differential diagnosis of an intraparenchymal solid splenic mass.
I would like to acknowledge our technical staff Mrs Philomena and Ms Maria and the Management of our institution.