Calcified Angioleiomyoma on the Dorsum of the Hand of a Patient With End-Stage Renal Disease: A Case Report

Introduction

Angioleiomyoma is a benign tumor of smooth-muscle origin commonly found in the lower extremities [1]. However, its incidence in the upper extremities and particularly the hand is low [2]. A review reported that angioleiomyomas account for less than 1% of all soft-tissue upper-extremity tumors [3]. Calcification in angioleiomyoma is even more uncommon and can pose diagnostic challenges, especially in ESRD patients, who have a predisposition to abnormal soft-tissue and vascular calcification. This calcification is typically dystrophic, resulting from long-standing degenerative changes or ischemic necrosis within the tumor, a process distinct from the metastatic calcification seen in metabolic disorders [4]. Here, we present a rare case of calcified angioleiomyoma in the hand of an ESRD patient and review the critical diagnostic features.

Case Report

A 46-year-old man had a slowing enlarging, mild, painful mass on the dorsal side of his left hand. The mass had started to grow in recent years with accompanied pain. He was on regular hemodialysis for 10 years because of ESRD. He had no other underlying disease or trauma history on the hand.

The mass was firm, non-mobile, and slightly tender, measuring 3×2 cm on the dorsal aspect of the left hand. The mass was subcutaneous with no obvious changes in the overlying skin, without infection sign or neurologic deficit.

Simple radiographs showed a well-demarcated soft-tissue mass with irregular internal punctate and curvilinear calcifications, without osseous involvement (Figure 1). MRI demonstrated a sharply defined, ovoid hypointense lesion on T1-weighted images with heterogenous, predominately hyperintensity on T2-weighted images, and multiple internal low-signal foci without enhancement. The lesion abutted the dorsal metacarpals without infiltration of bone or tendon (Figure 2). Blood tests revealed BUN 44.1 mg/dl, creatinine 13.07 mg/dl, calcium 8.7 mg/dl, and phosphorus 7.0 mg/dl.

Under brachial plexus block, the mass was totally excised. It was capsulated, tan, and firm. There was no adherence to tendons, nerves, or bone. Microscopically, the specimen showed interlacing bundles of bland spindle-shaped cells surrounding a thick-walled vessel. Extensive areas of basophilic dystrophic calcification were present. Proliferative bundles of smooth-muscle cells were also identified. Immunohistochemistry of smooth-muscle actin (SMA) showed diffuse strong cytoplasmic staining of tumor cells, confirming smooth-muscle differentiation (Figure 3).

The postoperative course was uneventful, with reduced pain. No recurrence or complications were noted at the 1-year follow-up.

Discussion

Angioleiomyoma typically presents as a slow-growing, painful mass, most commonly in the lower extremities and with a predominance in females [1]. Angioleiomyoma is a benign tumor composed of smooth-muscle bundles that arise from the tunica media of the subcutaneous blood vessels [5,6]. Involvement of the hand is rare, estimated at less than 5% of all cases due to the paucity of smooth muscles in the vasculature of the hand [2].

Calcification is uncommon in angioleiomyoma but should prompt consideration of dystrophic processes, particularly in patients with metabolic disorders such as ESRD. Calcifications are classified into dystrophic and metastatic calcification [4], although calcified angioleiomyomas are rare. Dystrophic calcifications can be due to minor trauma, vascular contractures, degenerative changes, and ischemic necrosis [7], but metastatic calcification results from systemic metabolic imbalances, such as hypercalcemia or hyperphosphatemia, and is the underlying mechanism of tumoral calcinosis, which presents as periarticular calcium deposits [8]. In ESRD patients, tumoral calcinosis is a non-neoplastic cause of periarticular, lobulated, dense calcified masses, often related to disturbances in calcium phosphate metabolism and secondary hyperparathyroidism [9]. Tumoral calcinosis classically presents as multilobulated, amorphous periarticular calcified masses, frequently on extensor surfaces of large joints and less commonly in the hand. Our patient presented with significantly elevated phosphorus, BUN, and creatinine levels, consistent with his ESRD status. Although his serum calcium was within the normal range, the resulting calcium-phosphorus (Ca x P) product was elevated (60.9 mg2/dl2). This state of hyperphosphatemia and high Ca x P product is a well-known driver for metastatic calcification, the underlying pathophysiology of tumoral calcinosis [10]. This metabolic profile made tumoral calcinosis a strong initial diagnostic possibility and created the primary diagnostic challenge presented in this case.

For diagnosis, imaging is key for preoperative assessment. MRI is helpful for determining tumor extent and differentiating it from other soft-tissue masses, although it is not diagnostic.

Other considerations for a painful, calcified hand mass include tumoral calcinosis, calcified ganglion cyst, giant cell tumor of tendon sheath, glomus tumor, synovial osteochondromas, and soft-tissue sarcoma [11]. Differentiating these calcified masses is critical. Tumoral calcinosis typically presents as large, amorphous, and multilobulated periarticular calcifications on radiographs, histologically showing amorphous calcium phosphate deposits surrounded by foreign-body giant cell reaction, but lacking neoplastic spindle cells. In contrast, our patient’s calcified angioleiomyoma showed punctate and curvilinear calcifications within a well-defined soft-tissue mass, and histopathology confirmed SMA-positive spindle cells surrounding vessels with dystrophic calcification, not metastatic. Other mimics, such as a calcified ganglion cyst, typically show peripheral or mural calcification of a T2-hyperintense cystic structure. Giant cell tumors of the tendon sheath can show calcification, but are typically T1/T2 hypointense due to hemosiderin deposits [11].

A review of the literature revealed very few reported cases of calcified angioleiomyoma of the hand. Recent case series have described the features of angioleiomyoma in the hand, often presenting as painful nodules without complex diagnostic features [3,12]. Other reports focusing on the calcified variant have detailed the histopathological mechanism of dystrophic calcification [4,7]. Our case is unique not only due to the rare presentation of a calcified variant in the hand but also due to the patient’s long-term hemodialysis. This comorbidity created a significant diagnostic challenge, mimicking tumoral calcinosis, a condition well-documented in hemodialysis patients [9,10]. Marco et al [8] reported a rare case of an acral angioleiomyoma co-existing with tumoral calcinosis, underscoring this clinical dilemma. While other reports focused on the dystrophic nature of the calcification [4,7], our case report uniquely underscores the need to differentiate this process from the metastatic calcification prevalent in ESRD.

For final diagnosis, histopathology is the gold standard for diagnosis of angioleiomyoma, with characteristic bundles of smooth-muscle cells and often thick-walled vessels. The SMA immunostaining helps distinguish angioleiomyoma from other spindle cell neoplasms [12].

Complete excision is a curative treatment. Malignant transformation is exceedingly rare, and recurrence is uncommon when calcified angioleiomyoma is excised with clear margins.

Conclusions

Calcified angioleiomyoma should be included in the differential diagnosis of a calcified, painful soft-tissue mass of the hand, especially in patients with ESRD. Surgical excision of calcified angioleiomyoma is a curative treatment with promising results. Combining clinical, imaging, and histopathological assessment is essential for accurate diagnosis and management.