Confusion-specimen mix-up in dermatopathology and measures to prevent and detect it

Abstract

Maintaining patient identity throughout the biopsy pathway is critical for the practice of dermatology and dermatopathology. From the biopsy procedure to the acquisition of the pathology report, a specimen may pass through the hands of more than twenty individuals in several workplaces. The risk of a mix-up is considerable and may account for more serious mistakes than diagnostic errors. To prevent specimen mix-up, work processes should be standardized and automated wherever possible, e.g., by strict order in the operating room and in the laboratory and by adoption of a bar code system to identify specimens and corresponding request forms. Mutual control of clinicians, technicians, histopathologists, and secretaries, both simultaneously and downstream, is essential to detect errors. The most vulnerable steps of the biopsy pathway, namely, labeling of specimens and request forms and accessioning of biopsy specimens in the laboratory, should be carried out by two persons simultaneously. In preceding work steps, clues must be provided that allow a mix-up to be detected later on, such as information about clinical diagnosis, biopsy technique, and biopsy site by the clinician, and a sketch of the specimen by the technician grossing it. Awareness of the danger of specimen mix-up is essential for preventing and detecting it. The awareness can be heightened by documentation of any error in the biopsy pathway. In case of suspicion, a mix-up of specimens from different patients can be confirmed by DNA analysis.

Keywords: biopsy; error; histopathology; mix-up; patient safety; quality improvement.

Figure 1.

Slides with handwritten and printed pathology numbers. Even with clear handwriting, characters do not look exactly the same. For example, the lower horizontal bar of the number 2 on the middle slide is rather short; as a consequence, the number might be read erroneously as 7. Among thousands of slides, there are always some handwritten characters that may be misread. Printed numbers prevent such errors. [Copyright: ©2014 Weyers.]

Figure 2.

Entry of data from the request form in the computer. (A) Correct: request forms lie on top of one another so that only the uppermost one is visible. After completion of the entry, the uppermost form is turned over and is placed back-side-up on the pile of finished forms on the left. (B) False: Request forms of several specimens are scattered across the desk. In case of a distraction, e.g., through a telephone call, the risk is considerable that data from an unrelated request form will be entered when resuming work. [Copyright: ©2014 Weyers.]

Figure 2.

Entry of data from the request form in the computer. (A) Correct: request forms lie on top of one another so that only the uppermost one is visible. After completion of the entry, the uppermost form is turned over and is placed back-side-up on the pile of finished forms on the left. (B) False: Request forms of several specimens are scattered across the desk. In case of a distraction, e.g., through a telephone call, the risk is considerable that data from an unrelated request form will be entered when resuming work. [Copyright: ©2014 Weyers.]

Figure 3.

In a patient in whom five biopsies were performed, specimens 3 and 4 cannot distinguished from one another because Roman numerals were used for labeling sample bottles. The Roman numeral 4 cannot be recognized clearly. [Copyright: ©2014 Weyers.]

Figure 4.

Because the top of one of those sample bottles was not closed tightly, formalin leaked out. The bottles were labeled with a permanent marker pen that was dissolved by formalin. As a consequence, the specimens in the sample bottles cannot be correlated reliably with the biopsy sites noted on the request forms. [Copyright: ©2014 Weyers.]

Figure 5.

The adhesive labels used to mark those sample bottles did not adhere but became detached. As a result, sample bottles cannot be distinguished from one another. The only option to dissolve this dilemma is correlation of histopathologic findings with the diagnoses and biopsy sites noted on the request forms. If biopsy sites and diagnoses are similar, however, correlation of biopsy specimens and request forms becomes a guessing game. [Copyright: ©2014 Weyers.]

Figure 6.

Correlation of sample bottles and request forms in the laboratory. The envelopes contain sample bottles and request forms of several patients. A large workspace for laying out request forms and sample bottles helps to prevent confusion of them. Sample bottles are placed on top of the corresponding request forms. Subsequently, bottles and request forms are marked with adhesive labels containing the pathology number and a corresponding bar code. The correlation of specimens with request forms and the numbering of them should be carried out by two persons who can control one another mutually. [Copyright: ©2014 Weyers.]

Figure 7.

Once sample bottles and request forms have been numbered, they are arranged in a row, corresponding to a row of tissue cassettes carrying the same numbers. Specimens are then dissected and put into tissue cassettes. The pathology numbers on sample bottles and tissue cassettes must be checked for concordance before taking out and dissecting the specimen. [Copyright: ©2014 Weyers.]

Figure 8.

Following dissection of specimens, many tissue cassettes with biopsy specimens of different patients are put in a basket and are processed in a tissue processor in order to dehydrate them and to prepare them for paraffin embedding. [Copyright: ©2014 Weyers.]

Figure 9.

Following procession of tissue, tissue cassettes are taken out of the tissue processor and are once again arranged in a row according to ascending pathology numbers. Paraffin blocks are arranged in the same fashion. The pathology numbers on tissue cassettes and blocks must be checked for concordance before opening the next cassette. Only one cassette should be opened at a time. Pincers must be cleared before taking out the next specimen in order to prevent transmission of fragments of tissue into a wrong block. [Copyright: ©2014 Weyers.]

Figure 10.

Before cutting sections at the microtome, blocks are cooled on a refrigerated plate. They are arranged in a row according to ascending pathology numbers and corresponding to a row of slides at the other side of the microtome. [Copyright: ©2014 Weyers.]

Figure 11.

Before clinching the next paraffin block to the microtome, the pathology number on the block and the slide must be checked for concordance and the blade of the microtome cleared from remnants of paraffin or tissue. By moving the block up and down across the blade, serial sections are cut that are connected by paraffin, resulting in thin ribbons of tissue. [Copyright: ©2014 Weyers.]

Figure 12.

Ribbons of tissue are transferred to a warm water bath where they are allowed to float on the surface before being scooped up onto a slide placed under the water level. If fragments of tissue become detached, they remain on the surface of the water bath and may be transferred onto another slide. In order to prevent such “floaters,” the water must be kept clean and must be changed at regular intervals. [Copyright: ©2014 Weyers.]

Figure 13.

(A) Biopsy from the chin of a 34-year-old patient showing typical signs of a verruca vulgaris, namely, acanthosis with elongated rete ridges bent toward the center of the lesion, papillomatosis, hypergranulosis with koilocytes, and compact orthokeratosis with narrow columns of parakeratosis above elongated papillae. In addition to two sections of the wart, there is another piece of tissue on the left. (B) The section of tissue on the left shows crowded nuclei in the lower layers of the epidermis, some hyperchromatic nuclei, loss of the granular layer, and parakeratosis with many nuclei per unit area. These are features of a solar keratosis. The piece of tissue does not belong on this slide but is presumably a “floater” from the water bath. [Copyright: ©2014 Weyers.]

Figure 13.

(A) Biopsy from the chin of a 34-year-old patient showing typical signs of a verruca vulgaris, namely, acanthosis with elongated rete ridges bent toward the center of the lesion, papillomatosis, hypergranulosis with koilocytes, and compact orthokeratosis with narrow columns of parakeratosis above elongated papillae. In addition to two sections of the wart, there is another piece of tissue on the left. (B) The section of tissue on the left shows crowded nuclei in the lower layers of the epidermis, some hyperchromatic nuclei, loss of the granular layer, and parakeratosis with many nuclei per unit area. These are features of a solar keratosis. The piece of tissue does not belong on this slide but is presumably a “floater” from the water bath. [Copyright: ©2014 Weyers.]

Figure 14.

End control of slides in the laboratory. Slides are laid out on trays according to ascending pathology numbers. Before they are forwarded for microscopy, they are checked for the identical ascending sequence of pathology numbers on slides and request forms and for concordance of the shape of specimens in paraffin blocks and on slides. [Copyright: ©2014 Weyers.]

Figure 15.

In a 58-year-old patient, two biopsies were performed under the clinical diagnosis of a melanocytic nevus. On the request form, specimen 1 was said to be an excisional biopsy from the right arm, and specimen 2 a punch biopsy from the cheek. (A, B) Specimen 1 shows a punch biopsy of a melanoma in situ characterized by a proliferation of single melanocytes, many of which are present in the upper reaches of the epidermis. The dermis shows marked solar elastosis and a large sebaceous gland. (C, D) Specimen 2 shows the compound stage of a Clark’s nevus. The lesion is symmetrical and sharply circumscribed, melanocytes are distributed in regular fashion, and there are no melanocytes in the upper reaches of the epidermis. There is no solar elastosis. The lesion does not extend to lateral margins. Those two specimens have been mixed-up. This can be concluded from type of excision (complete for the nevus, incomplete for the melanoma), the anatomy (the large sebaceous gland in Figure 15A indicates the cheek as the biopsy site), and the association of the melanoma with marked solar elastosis (also indicating the cheek as the biopsy site). Without the precise information on the request form, the mix-up of specimens would not have been detected. (E) Even with this information, the mix-up would not have been detected in the case of a superficial shave biopsy including only epidermis and papillary dermis, but not the sebaceous gland and the pronounced solar elastosis in the upper reticular dermis. [Copyright: ©2014 Weyers.]

Figure 15.

In a 58-year-old patient, two biopsies were performed under the clinical diagnosis of a melanocytic nevus. On the request form, specimen 1 was said to be an excisional biopsy from the right arm, and specimen 2 a punch biopsy from the cheek. (A, B) Specimen 1 shows a punch biopsy of a melanoma in situ characterized by a proliferation of single melanocytes, many of which are present in the upper reaches of the epidermis. The dermis shows marked solar elastosis and a large sebaceous gland. (C, D) Specimen 2 shows the compound stage of a Clark’s nevus. The lesion is symmetrical and sharply circumscribed, melanocytes are distributed in regular fashion, and there are no melanocytes in the upper reaches of the epidermis. There is no solar elastosis. The lesion does not extend to lateral margins. Those two specimens have been mixed-up. This can be concluded from type of excision (complete for the nevus, incomplete for the melanoma), the anatomy (the large sebaceous gland in Figure 15A indicates the cheek as the biopsy site), and the association of the melanoma with marked solar elastosis (also indicating the cheek as the biopsy site). Without the precise information on the request form, the mix-up of specimens would not have been detected. (E) Even with this information, the mix-up would not have been detected in the case of a superficial shave biopsy including only epidermis and papillary dermis, but not the sebaceous gland and the pronounced solar elastosis in the upper reticular dermis. [Copyright: ©2014 Weyers.]

Figure 15.

In a 58-year-old patient, two biopsies were performed under the clinical diagnosis of a melanocytic nevus. On the request form, specimen 1 was said to be an excisional biopsy from the right arm, and specimen 2 a punch biopsy from the cheek. (A, B) Specimen 1 shows a punch biopsy of a melanoma in situ characterized by a proliferation of single melanocytes, many of which are present in the upper reaches of the epidermis. The dermis shows marked solar elastosis and a large sebaceous gland. (C, D) Specimen 2 shows the compound stage of a Clark’s nevus. The lesion is symmetrical and sharply circumscribed, melanocytes are distributed in regular fashion, and there are no melanocytes in the upper reaches of the epidermis. There is no solar elastosis. The lesion does not extend to lateral margins. Those two specimens have been mixed-up. This can be concluded from type of excision (complete for the nevus, incomplete for the melanoma), the anatomy (the large sebaceous gland in Figure 15A indicates the cheek as the biopsy site), and the association of the melanoma with marked solar elastosis (also indicating the cheek as the biopsy site). Without the precise information on the request form, the mix-up of specimens would not have been detected. (E) Even with this information, the mix-up would not have been detected in the case of a superficial shave biopsy including only epidermis and papillary dermis, but not the sebaceous gland and the pronounced solar elastosis in the upper reticular dermis. [Copyright: ©2014 Weyers.]

Figure 15.

In a 58-year-old patient, two biopsies were performed under the clinical diagnosis of a melanocytic nevus. On the request form, specimen 1 was said to be an excisional biopsy from the right arm, and specimen 2 a punch biopsy from the cheek. (A, B) Specimen 1 shows a punch biopsy of a melanoma in situ characterized by a proliferation of single melanocytes, many of which are present in the upper reaches of the epidermis. The dermis shows marked solar elastosis and a large sebaceous gland. (C, D) Specimen 2 shows the compound stage of a Clark’s nevus. The lesion is symmetrical and sharply circumscribed, melanocytes are distributed in regular fashion, and there are no melanocytes in the upper reaches of the epidermis. There is no solar elastosis. The lesion does not extend to lateral margins. Those two specimens have been mixed-up. This can be concluded from type of excision (complete for the nevus, incomplete for the melanoma), the anatomy (the large sebaceous gland in Figure 15A indicates the cheek as the biopsy site), and the association of the melanoma with marked solar elastosis (also indicating the cheek as the biopsy site). Without the precise information on the request form, the mix-up of specimens would not have been detected. (E) Even with this information, the mix-up would not have been detected in the case of a superficial shave biopsy including only epidermis and papillary dermis, but not the sebaceous gland and the pronounced solar elastosis in the upper reticular dermis. [Copyright: ©2014 Weyers.]

Figure 15.

In a 58-year-old patient, two biopsies were performed under the clinical diagnosis of a melanocytic nevus. On the request form, specimen 1 was said to be an excisional biopsy from the right arm, and specimen 2 a punch biopsy from the cheek. (A, B) Specimen 1 shows a punch biopsy of a melanoma in situ characterized by a proliferation of single melanocytes, many of which are present in the upper reaches of the epidermis. The dermis shows marked solar elastosis and a large sebaceous gland. (C, D) Specimen 2 shows the compound stage of a Clark’s nevus. The lesion is symmetrical and sharply circumscribed, melanocytes are distributed in regular fashion, and there are no melanocytes in the upper reaches of the epidermis. There is no solar elastosis. The lesion does not extend to lateral margins. Those two specimens have been mixed-up. This can be concluded from type of excision (complete for the nevus, incomplete for the melanoma), the anatomy (the large sebaceous gland in Figure 15A indicates the cheek as the biopsy site), and the association of the melanoma with marked solar elastosis (also indicating the cheek as the biopsy site). Without the precise information on the request form, the mix-up of specimens would not have been detected. (E) Even with this information, the mix-up would not have been detected in the case of a superficial shave biopsy including only epidermis and papillary dermis, but not the sebaceous gland and the pronounced solar elastosis in the upper reticular dermis. [Copyright: ©2014 Weyers.]