Cytology of primary skin tumors

Epidermoid Cyst: An Esthetic Challenge, If Neglected-A Comprehensive Analysis of 217 Cases

Background

An epidermoid cyst is a benign keratin-filled cyst, commonly located in the face, scalp, neck, and trunk. Although it is a common benign cystic neoplasm, large series of analyses in English literature are still scarce. To comprehend the clinical and pathological variation of epidermoid cysts in the sub-Himalayan region of India, as well as their clinical implications for late diagnosis, a retrospective study on epidermoid cysts was conducted.

Materials and Methods

This was a retrospective observational study conducted on 217 cases of epidermoid cyst subjected for fine-needle aspiration cytology over a period of 3.6 years (from 2018 to 2021). The clinical details and other epidemiological data were archived from the pathology requisition forms.

Results

It showed slight male preponderance with head and neck site as the most common area. Most patients were adults. Few uncommon sites were also seen namely breast, parotid, epididymis, and tonsils. Few large lesions were identified measuring up to 10 cm. The skin changes were seen in 5.5% cases, 0.9% cases show extreme ulceration, and 4.1% cases show foreign body giant cell reactions. Due to the province's steep terrain and limited access to medical services, the majority of patients arrived at out patient department (OPD) late.

Conclusion

The findings suggest that fine-needle aspiration can be used as a quick diagnostic test even in remote areas by the general practitioner who can send the slides for evaluation to a pathologist. Many times, clinically looking epidermoid cyst can reveal certain challenging entities such as a biphasic fibroepithelial tumor with cystic squamous metaplasia and proliferating pilar tumor in our series. The study of this lesion is also needed for early diagnosis as long-standing lesion may rupture and cause requirement of extensive treatment followed cosmetic impairment.

Cytomorphology of Skin Adnexal Tumors: A Tale of Two Scalp Swellings

The primary and metastatic tumors of the skin can be effectively diagnosed by fine needle aspiration cytology (FNAC); however, the cytomorphological features of skin adnexal tumors are rarely described in the literature. We hereby describe the cytological features of two histologically confirmed cases of benign skin adnexal tumors. Case 1 is of a 46-year-old female who presented with an elevated firm nodule over the scalp. A cytological diagnosis of benign adnexal tumor possibly of sebaceous origin was given. The nodule was excised and histopathological examination confirmed the diagnosis of sebaceoma. Case 2 is of a 19-year-old male who presented with a pigmented scalp swelling. Cytomorphological features were suggestive of benign skin adnexal tumor with foci of melanin pigment. The swelling was excised and histopathological examination confirmed the diagnosis of eccrine poroma. To the best of our knowledge, only one previous report of sebaceoma and no report of eccrine poroma describing the cytological findings of these two tumors exist. We report these two cases of benign skin adnexal tumors to discuss the cytological features and the potential diagnostic dilemma that they pose to the cytologist.

Case of chondroid syringoma mimicking a nodular hidradenoma: A diagnostic pitfall on cytopathology

Limited literature is available on the use of fine needle aspiration (FNA) for skin tumors. Awareness of cytological features of these lesions is important to prevent misdiagnosis. A 45-year-old male, presented with slowly growing swelling over the thigh since 4 years. FNA from multiple sites yielded highly cellular smears with a dual cell population consisting of cells with small round nucleus scanty cytoplasm and polygonal cells with moderate to abundant cytoplasm. Extracellular basement membrane like material was also noted. A diagnosis of benign adnexal neoplasm, suggestive of nodular hidradenoma was made. Paraffin sections showed an encapsulated dermal tumor composed of ductal and myoepithelial cells in ducts, sheets, strands with chondromyxoid stroma. A final diagnosis of chondroid syringoma was given following evaluation of histopathology slides and Immunohistochemistry. FNA interpretation of skin tumors can be challenging since literature is limited. The placement of tumors into benign or malignant category is realistic and can direct management guidelines. Greater awareness of these lesions and following stringent diagnostic criteria can help in establishing a more accurate diagnosis.

Fine-needle aspiration cytology in primary cutaneous tumors

BACKGROUND

Fine-needle aspiration biopsy (FNAB) is occasionally used in the evaluation of primary skin tumors. However, in routine evaluation of any soft tissue swelling we encounter the cases of skin lesions. It is essential to know FNAB features of skin lesions.

MATERIALS AND METHODS

We present detailed cytomorphologic features with histologic correlation of 28 primary skin tumors, evaluated over a period of 4 years.

RESULT

An accurate diagnosis was provided in 42.8% cases, while benign or malignant nature was correctly established in 82.1% cases.

CONCLUSIONS

The most common cause of incorrect diagnosis was sampling error and a definitive diagnosis was not provided in adnexal tumors due to overlap of cytologic features and lack of availability of architectural features. The knowledge of cytological features of the skin adnexal tumor is helpful to avoid any mistaken diagnosis. Diagn. Cytopathol. 2017;45:681-688. © 2017 Wiley Periodicals, Inc.

Diagnostic Evaluation of Skin Adnexal Tumors by Fine-Needle Aspiration Cytology

BACKGROUND

The diagnosis of skin adnexal tumors is usually based on histopathology. However, fine-needle aspiration cytology (FNAC) can be of great help and shows a high degree of correlation to the final diagnosis. It is helpful in many situations where skin lesions are a manifestation of certain systemic syndromes and aids to the formation of precise treatment plans.

MATERIALS AND METHODS

This prospective study was carried out to assess the diagnosis of skin adnexal tumors based on FNAC and their comparison with histopathological diagnoses. There were 14 patients with FNAC and histopathological follow-up in whom a final diagnosis of skin adnexal tumor was made. The results of FNAC were compared with histopathological diagnoses for complete correlation, partial correlation (cases where an FNAC diagnosis of skin adnexal tumor was made but a precise diagnosis of the subtype was not possible) or no correlation (where FNAC failed to diagnose a skin adnexal tumor).

RESULTS

Among the 14 cases of skin adnexal tumor, there was total correlation between the FNAC diagnosis and final histopathological diagnosis in 8 cases (57.1%) and a partial correlation in 4 cases (28.5%). There was no correlation of the FNAC diagnosis with the histopathological diagnosis in only 2 cases (14.3%).

CONCLUSIONS

FNAC is very useful in making a diagnosis of skin adnexal tumors and helps in the management of the patient.

Atypical Hidradenoma Mimicking Primary Mammary Carcinoma on Breast Fine-Needle Aspiration: A Case Report with Long-Term Follow-Up

BACKGROUND

Fine-needle aspiration (FNA) is well-established as an accurate technique for the diagnosis of palpable breast masses. While the differential diagnosis of such lesions usually focuses on benign or malignant mammary proliferations, a subset of breast neoplasms arises from skin and soft tissue. Skin adnexal neoplasms such as hidradenoma can pose a particular pitfall on breast FNA cytology (FNAC) as epithelial proliferations that are not of ductal or lobular origin.

CASE

A 59-year-old female presented with a superficial breast mass. FNAC revealed a hypercellular lesion with marked nuclear atypia that was highly suspicious for carcinoma. However, at partial mastectomy, the histological features of the tumor were consistent with atypical hidradenoma. Negativity for estrogen receptor (ER) and progesterone receptor (PR) confirmed the diagnosis. Eighteen years later, the patient remains free of recurrence or metastasis.

CONCLUSIONS

This report offers the first description of findings of atypical hidradenoma on FNAC. In the breast, its high cellularity and nuclear atypia can mimic a primary mammary carcinoma on FNAC. Although breast and skin adnexal tumors show a immunohistochemical overlap, negative ER and PR stains in a low-grade tumor can suggest a nonmammary lesion. Skin adnexal neoplasms should be considered in the differential diagnosis of superficial breast tumors.

Clear-cell hidradenoma in a child: a diagnostic dilemma for the cytopathologist

Primary cutaneous tumors are infrequently subjected to fine needle aspiration cytology. As a result, the cytological reports of skin adnexal tumors like hidradenoma are scarce in the available literature. A young boy with a painless nodule on forehead underwent fine needle aspiration. The smears showed clusters of epithelial cells containing blue cytoplasm, some of which had vacuolated cytoplasm with mild nuclear pleomorphism and occasional larger hyperchromatic nucleus. The cytological features, in conjunction with the clinical examination, suggested a skin appendageal tumor. Though nuclear pleomorphism and occasional larger nucleus posed a cytological diagnostic challenge, a diagnosis of benign appendageal tumor was suggested, considering the young age of the patient. This was later confirmed as a clear-cell hidradenoma on excision biopsy. The cytopathologist should consider skin appendageal tumors during evaluation of cutaneous nodules. An accurate diagnosis requires a close clinico-pathologic correlation.

Epidermal inclusion cyst: cytomorphological features and differential diagnosis

Aspirates from 162 epidermal inclusion cysts (EIC) from 157 patients were analyzed in order to elaborate on specific cytologic features. The most common site involved was the head and neck region (96 cases; 59.2%). The maximum patients were in the 3rd and 4th decades of life. Aspirates from EIC showed a clear background, with high cellularity, and nucleate and anucleate squames. Keratinous material was seen in some cases but the amount was less compared with the cellular elements. In 31 cases, a diagnosis of infected EIC was made on the basis of dense inflammatory infiltrate in addition to the squames. Histopathology was available in 56 cases out of which EIC was diagnosed in 45 cases. The remaining 11 cases were dermoid cyst (5 cases), branchial cyst (2 cases), pilomatricoma (2 cases), and sebaceous and thyroglossal cyst (1 case each). Thus, EIC should be differentiated from other squamous cell containing lesions.

Cytologic features of primary, recurrent, and metastatic dermatofibrosarcoma protuberans

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a low-grade spindle cell neoplasm involving both dermis and subcutis. Its diagnosis may be difficult to render from cytologic smears, as it shares some features with other spindle cell lesions occurring in the skin and soft tissue.

METHODS

Fourteen aspiration smears from 12 patients with primary, recurrent, or metastatic DFSP, examined by fine-needle aspiration biopsy (FNAB), were reviewed and compared with corresponding surgical specimens (13 aspirates) and clinical data (one aspirate). The cytologic features of DFSP were evaluated. Other spindle cell lesions in the differential diagnoses were discussed.

RESULTS

Unequivocal spindle cell sarcoma diagnoses were rendered in nine aspirates, six of which were labeled correctly as DFSP in the original reports. In three aspirates, the preoperative diagnoses were inconclusive with regard to whether the tumors were benign or malignant. Two aspirates were diagnosed erroneously as benign spindle cell lesions. Cytologic features included tight clusters of bland spindle cells embedded in a collagenous/fibrillar and, often, metachromatic matrix along with dissociated, uniform, or slightly atypical spindle cells or bare nuclei. Tissue fragments showing a storiform pattern and entrapped fat tissue, reported in previous series, were less characteristic, presenting in nine and seven aspirates, respectively.

CONCLUSIONS

Correct subtyping of DFSP in fine-needle aspiration smears can be difficult, due to its morphologic overlapping with other spindle cell lesions. A combination of cytology with ancillary studies and appropriate clinical information is crucial to establishing a correct diagnosis.

Pilomatrixoma: clinicopathologic study of 51 cases with emphasis on cytologic features

The clinical and pathologic features of 51 cases of pilomatrixoma found in our archives from 1990-1999 were reviewed, with emphasis on the cytopathologic features of the 22 cases that were sampled by fine-needle aspiration (FNA) biopsy prior to excision. Although uncommon, almost 20% of the pilomatrixomas in this series occurred in adults over age 30. Of the commonly reported features, the presence of basaloid cells and ghost cells in FNA smears, associated with a cutaneous location of the lesion, was sufficient for a confident cytologic diagnosis of pilomatrixoma. The presence of foreign body-type giant cells, nucleated squamous cells, and calcification, alone or in combination, was less specific, but supported a diagnosis of pilomatrixoma. Although infrequently reported, prominent nucleoli in basaloid cells and smears containing refractile keratin clumps were very useful clues in the diagnosis of pilomatrixoma. Finally, the routine use of cell blocks is recommended because in many of the cases presented ghost cells were fragmented or obscured in smears, but were more readily identified in cell block sections.

Cytologic features of angioleiomyoma: cytologic-histologic study of 10 cases

Fine-needle aspiration (FNA) features in 10 angioleiomyomas (ALM) were evaluated and correlated to histological features and clinical data. The tumors developed in the skin or subcutaneous tissue of the lower extremities (eight), the shoulder (one), and the lower arm (one). Eight tumors were painful or tender. Cytological specimens showed moderate or sparse cellularity. The most frequent findings were uniform spindle cells, seen in nine smears. In eight of these, the spindle cells were admixed with smooth muscle cells and fragments of collagenous tissue in varying proportions. The occurrence of macrophages and fat cells was less specific, being present in three of nine smears. One aspirate contained some "ganglion-like" cells and a multinucleated giant cell. Smears from ALM are not sufficiently characteristic to permit a histotype diagnosis, but together with typical clinical data (painful or tender nodule) may help to exclude other skin or subcutaneous lesions.

Fine-needle aspiration features of pilomatrixoma

BACKGROUND

Pilomatrixoma (PMX) is a benign skin neoplasm of hair matrix origin. The fine-needle aspiration (FNA) features of PMX frequently lead to a misdiagnosis of carcinoma.

METHODS

Nine cases of PMX in which a preoperative FNA was performed were reviewed. The cytologic features were compared with the histologic appearance of corresponding surgical specimens as well as with cytologic features of tumors that arose in the differential diagnosis.

RESULTS

Unequivocal benign diagnoses were rendered in three cases; the correct preoperative diagnosis of PMX was rendered in two of these cases and considered in an additional case. In four additional cases, carcinoma was diagnosed or could not be excluded. A noncommittal diagnosis of epithelial tumor, most likely of skin adnexal origin, was rendered in an additional single case. Retrospective review of the FNA smears in all nine instances disclosed cytologic features that corresponded well with the histologic components of PMX. Diagnostic cytologic features included cellular aspirates; clusters of small, primitive-appearing basaloid epithelial cells; a high nuclear-cytoplasmic ratio; evenly dispersed chromatin; prominent nucleoli; pink, fibrillary material enveloping clusters of basaloid cells; multinucleated giant cells; and sheets of ghost cells.

CONCLUSIONS

The FNA cytologic diagnosis of PMX may be extremely difficult; its distinction from various primary cutaneous carcinomas is most problematic. Recognition of a unique constellation of cytologic features in FNA smears in the appropriate clinical context is most helpful in making this distinction.

Cytology of metastatic cutaneous basal cell carcinoma

Although basal cell carcinoma is the most common malignant skin tumor, it rarely metastasizes. Because of the infrequency of basal cell carcinoma metastases, the cytomorphologic findings have not been well documented. We retrospectively reviewed the cytologic findings of six cases of metastatic basal cell carcinoma from two patients. Five of these specimens were fine-needle aspiration biopsies, and one was a bronchial brush specimen. All cases were confirmed by and compared to either the concurrent tissue biopsy or to a previous surgical specimen. The microscopic findings of these specimens reveal tight clusters of cells with high nuclear to cytoplasmic ratio. The nuclei were crowded and overlapping, and on Diff Quik stain, peripheral palisading of nuclei could be appreciated. The small hyperchromatic nuclei were round to oval with finely granular chromatin. Nucleoli were inconspicuous. Basophilic cytoplasm was scant with indistinct borders. Cytologic findings of basal cell carcinoma have not been well documented in the English literature. Our experience suggests that there are unique cytormorphologic features of metastatic basal cell carcinoma and that in the right setting such a diagnosis can be rendered.

Cytologically interesting cases of primary skin tumors and tumor-like conditions identified by fine-needle aspiration biopsy

The aims of this study are to depict the special but constant cytomorphologic features which allow a distinction among grossly similar skin tumors and to show that cytological assessment of many uncommon skin lesions is possible. The fine-needle aspiration findings of 181 cytologically interesting cases of primary skin tumors selected from 2,301 primary skin lesions examined in our department from 1990-1995 are described. Seventy-five cases were cytologically reported as benign and 89 as malignant. In 17 cases the aspirated material was considered inconclusive, although some possible diagnoses could be supported. A subsequent histological examination followed the cytologic assessment in all cases. Fine-needle aspiration cytology identified uncommon cutaneous cystic lesions (bronchogenic, dermoid, myxoid), benign and malignant tumors of epidermal appendages such as chondroid syringomas, cylindromas, pilomatrixomas, sebacecous carcinoma, and primary adenoid cystic carcinoma, as well as tumors of the dermis and subcutaneous fat. Primary cutaneous lymphomas were also diagnosed and classified morphologically and immunocytochemically. In our diagnoses of uncommon skin tumors new cytologic criteria were created and utilized and are described in this report in detail.

Fine-needle aspiration of Merkel cell carcinoma of the skin with cytomorphology and immunocytochemical correlation

Merkel cell carcinoma (MCC) of the skin is a rare, primary malignant skin neoplasm which can present as a cutaneous nodule. These neoplasms are seen primarily in the elderly and located in the head and neck area or extremities. Twenty-nine aspirates from primary and metastatic lesions obtained by percutaneous fine-needle aspiration in 19 patients have been studied. The cytomorphologic features, clinical information, and immunocytochemical (ICC) findings are detailed. Aspirate smears demonstrated small-to-intermediate-sized cells with a loosely cohesive pattern. Nuclei were round with finely granular chromatin and multiple, small nucleoli. Cells possessed a thin rim of cytoplasm, and infrequent pseudorosette formations were noted in cell groups. ICC results were universally positive for cytokeratin, which showed a paranuclear "dot-like" pattern. Neuron-specific enolase, epithelial membrane antigen, and S-100 protein were positive in varying degrees. Leukocyte common antigen was universally negative. The diagnosis of MCC of the skin by FNA can be made by applying cytologic features in addition to ancillary studies and clinical information.