Intraprostatic Pacinian corpuscle does exist!
Afiliação
(1)Imagepat, Laboratory of Pathology, Rio Vermelho, Salvador, BA, Brazil.
(2)Imagepat, Laboratory of Pathology, Rio Vermelho, Salvador, BA, Brazil; Hospital Universitário Professor Edgard Santos, Federal University of Bahia, Salvador, BA, Brazil.
Resumo
Pacinian corpuscle is a low threshold mechanoreceptor involved in the sensation of pressure, touch, and vibration. Its structure comprises a capsule, flat cells (Schwann-like glial cells, or lamellar cells) arranged in a concentric pattern of about 30 lamellae and a central core with an axon terminal. Pacinian corpuscles are commonly seen in dermis and subcutaneous tissues of the hands and feet and the digits, arm, neck, mesenteries, near joints, nipples, external genitalia, and periosteal and interosseous membranes.3 They are exceptionally rare in other locations and have been documented in urinary bladder, pancreas, lymph nodes and thymus. They have also been observed in developmental disorders such as meningoradiculoceles and cervical chondrocutaneous rests.8,9 We are aware of two previous reports of Pacinian corpuscles in the prostate,10,11 both of which were not in clear intraprostatic location. We report herein the finding of a radical prostatectomy specimen from a 64-year-old patient. It showed a prostatic adenocarcinoma, Gleason score 9 (4+5) (Grade group 5), with extraprostatic extension (pT3a). On microscopy, the periphery of the right apex showed—in addition to extensive prostatic malignancy—one bulbous onion-like formation measuring 1 mm (maximum diameter) in obvious intraprostatic location (Fig. 1). The corpuscle was located 0.5 mm deep from the external boundary of the prostate. Clinical history was unremarkable. In the case reported by Medlicott and colleagues, two corpuscles were described as located in the periphery of mid-gland and, based on the photomicrograph, at least one of them was in the extraprostatic tissue.10 In the first report of prostatic Pacinian corpuscle, location and level of occurrence was not provided although the photomicrograph suggests the presence of adipose (extraprostatic) tissue surrounding the structure.11 Extraprostatic tissue is known to harbour numerous and large paraganglia. In the bladder, Pacinian corpuscle can be seen within large paraganglia during the first months of life. In specimens of children older than 5 months, these structures are only seen separate.12 This observation suggests that paraganglia may be involved in the differentiation of Pacinian corpuscle during development. However, Pacinian corpuscles are exceptionally rare in the urinary bladder of adults. We confirm the occurrence of Pacinian corpuscles within intraprostatic tissues (Fig. 1). In all three documented cases to date, Pacinian corpuscles were surrounded by high-grade invasive acinar adenocarcinoma. Awareness of variations of normal histology is important to avoid misinterpretation of unusual findings.