Cutaneous Metastasis of Hormone Therapy-Resistant Prostate Adenocarcinoma to the Inguinal Region.

Dear Editor,

Adenocarcinoma of the prostate gland is the second most common malignancy in males, and it is well known to disseminate to bones, lymphatic nodes, and viscera. Skin metastases of prostatic origin are quite uncommon. The combination of clinical history, physical examination, laboratory tests, and routine pathology can often provide enough information for a conclusive diagnosis of metastatic prostatic adenocarcinoma.[1]

Herein we present an 86-year-old male patient with cutaneous metastasis of hormone therapy-resistant prostate adenocarcinoma to the inguinal region.

An 86-year-old man presented with 1-month history of multiple asymptomatic genital lesions. On dermatological examination, there were multiple erythematous papulonodules measuring 1–5 cm in diameter on the pubic and inguinal region [Figure 1]. The patient had been followed up with the diagnosis of prostate adenocarcinoma at the Urology Department for 15 years. The patient was consulted with us for the development of skin lesions. He was receiving leuprolide acetate subcutaneously every 3 months and bicalutamide 50 mg daily. His prostate-specific antigen (PSA) level was 6.9 ng/mL (N: 0–4 ng/mL) and free-PSA was 5.43 (N: 0–1). Other physical examination findings and laboratory investigations were normal. There was no lymphadenopathy on inguinal ultrasonography and no distant metastasis was detected on the other radiological examinations. A punch biopsy was performed from the lesion. Histopathological examination showed infiltration of the dermis by tumor cells arranged in a glandular pattern [Figure 2]. Immunohistochemical staining was positive for pancytoceratine (PanCK) and prostate-specific acid phosphatase (PSAP) [Figure 3]. The diagnosis was skin metastasis of prostate adenocarcinoma. Docetaxel treatment was started and medicated for six cycles. Local radiotherapy was performed. Significant improvement was achieved in skin metastases.

Figure 1

Multiple erythematous papulonodules variable in size on the pubic and inguinal region

Figure 2

Epithelial tumor with small adenoid structures and cribriform areas in dermis (HE x40)

Figure 3

PSAP positivity confirming the diagnosis of prostate adenocarcinoma (PSAP x40)

Cutaneous metastases of internal malignancies are uncommon, with rates ranging from 0.6% to 10%. Cutaneous spread of prostate cancer is very rare, representing less than 1% of all cutaneous metastasis. Cutaneous metastases from prostatic carcinoma are usually asymptomatic and may occur at single or multiple sites. Metastatic lesions are usually papules and nodules and they rarely ulcerate. The cutaneous lesions presented as multiple hard nodules in 56 cases (72%), a single nodule in 11 (14%), edema or lymphedema in 5 (7%), and unspecific rash in 5 (7%). The most frequent site for the cutaneous involvement was inguinal area and penis (28%), followed by abdomen (23%), head and neck (16%), chest (14%), extremities (10%), and back (9%).[2]

Although the mechanism of cutaneous involvement is not well-understood, suggested routes include embolization of vessels, dissemination through lymphatics, and through perineural lymphatics. Immunohistochemistry is an important tool in establishing the organ of origin when histology is not conclusive.[3] A large majority of metastatic adenocarcinomas are P501S positive (99%). A small subset of metastatic prostatic adenocarcinoma shows significant differences in staining intensity and extent of PSA and P501S and therefore combined use of these markers may result in increased sensitivity for detecting prostatic origin.[4]

Therapeutic options reported for similar cases of prostatic carcinoma with cutaneous metastasis are primarily palliative and include tumor excision, radiation, intralesional chemotherapy (i.e., leuprolide), and treatment of the primary neoplasia.[5] Other chemotherapy options may be used, as in our patient. We observed a significant regression of the skin metastases with docetaxel.

Skin metastasis generally occurs in advanced malignancy, but it can be seen alone without distant metastasis as in our patient. Although cutaneous metastasis is an uncommon presentation of prostate cancer, in rapidly growing cutaneous nodules, especially on the perineal region, prostate carcinoma should be kept in mind.

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Conflicts of interest

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